This distinguished philosopher was the elder son of the unfortunate Sir Everard Digby, who suffered death as one of the chief conspirators in the gunpowder plot. According to the best accounts, he was born in June 1603, and having been removed from the charge of his mother while still a child, received his education under the care of Archbishop Laud. At Oxford, whither he was sent at the age of fifteen, he displayed an aptitude for learning which led to the most confident expectation of his future celebrity. He left the university, however, after a residence of only two or three years, and having made the tour of the continent, attached himself to the court, obtained the honour of knighthood, and not long after, was made a gentleman of the bed chamber, a governor of Trinity house, and a commissioner of the navy. These appointments were followed by another still less conformable to his character as a scholar and philosopher. A fleet having been fitted out to chastise the Algerine pirates, and settle some disputes with the Venetians, Sir Kenelm received the command, and the success of the expedition raised him considerably in the estimation of his powerful friends. Of the high opinion entertained of him by his more learned associates, a strong proof was given by his late tutor, Mr. Allen of Oxford, who, at his demise, bequeathed him his splendid collection of books and manuscripts. Archbishop Laud continued also to regard him with an affection which did honour to them both, and counselled him in the most difficult passage of his life with equal kindness and gravity. A residence in France was productive of consequences, which finally induced Sir Kenelm to renounce those principles of Protestantism in which he had been carefully educated. That he was led to this step chiefly from a feeling of respect for his father's name, and by the unceasing solicitations of others, may be gathered from his own confession, that though he considered the subject for two years before he came to a decision, the works he read, during that time, were nearly all on the side of Catholicism. The first person, it appears, to whom he communicated his change of religion, was the archbishop, and in the letter which the primate wrote to him on the occasion, we find that he had unfolded his views with candour and modesty. "The way you took," says the prelate, "in concealing this your resolution of returning into that communion, and the reasons which you give, why you so privately carried it here, I cannot but approve. They are full of all ingenuity, tender and civil respects, fitted to avoid discontent in your friends, and scandal that might be taken by others, or contumely that might be returned upon yourself. And as are these reasons, so is the whole frame of your letter, (setting aside that I cannot concur in judgment,) full of discretion and temper, and so like yourself, that I cannot but love even that which I dislike in it; and though I shall never be other than that I have been to the worth of Sir Kenelm Digby, yet most heartily sorry I am, that a man, whose discourse did so much content me, should thus slide away from me before I had so much as suspicion to awaken me, and suggest that he was going." After expressing his sorrow still further, that he had not informed him of the state of his mind, and stating that he should not then enter into argument with him, he says, "In your power it was not to change, in mine it is not to make you change again. Therefore, to the moderation of your own heart, under the grace of God, I must and do now leave you for matter of religion, but retaining still with me, and entirely, all the love and friendship which your worth won from me, well knowing that all differences in opinion shake not the foundations of religion." From the allusions made in the conclusion of the letter, it is evident that Sir Kenelm exposed himself to the loss of many advantages, at least in his own country, by the sacrifice he made to feeling. "Had you written this to me with a restraint of making it further known, I should have performed that trust; but since you have submitted to me, what further knowledge of it I shall think fit to give to any other person, I have, as I took myself bound, acquainted his majesty with it, who gave a great deal of very good expression concerning you, and is not a little sorry to lose the service of so able a subject. I have likewise made it known in private to Mr. Secretary Cooke, who was as confident of you as myself: I could hardly believe your own letters, and he as hardly my relation. To my secretary, I must needs trust it, having not time to write it again out of my scribbled copy; but I dare trust the secrecy in which I have bound him. To others I am silent, and shall so continue till the thing open itself, and I shall do it out of reasons very like to those which you give, why yourself would not divulge it here. In the last place, you promise yourself that the condition you are in will not hinder me from continuing to be the best friend you have. To this I can say no more, than that I could never arrogate to myself to be your best friend, but a poor, yet respective friend of yours I have been, ever since I knew you; and it is not your change that can change me, who never yet left but where I was first forsaken, and not always there."
On Sir Kenelm's return to England he became a conspicuous member of the queen's party, and was employed by her to collect contributions from the Catholics when the king was preparing for his war with Scotland. The activity with which he performed this commission rendered him highly obnoxious to the popular party, and at the commencement of the civil war he was apprehended, and committed to Winchester house. His character for learning, however, was sufficiently respected to protect him from ignominious treatment. No stop was put to his intercourse with his friends, and, in 1643, he was set at liberty. It was to the interference of the queen-dowager of France that he owed this recovery of his freedom; but before being allowed to leave the kingdom, he was obliged to sign a paper in which he solemnly declared, "upon the faith of a Christian, and the word of a gentleman," that he would "neither directly nor indirectly, negotiate, promote, consent unto, or conceal any practice or design, prejudicial to the honour or the safety of the parliament." At the same time he was examined as to his knowledge of the archbishop's proceedings, and had thereby an opportunity of expressing, in the clearest terms, his conviction of the primate's entire devotion to the Protestant system.
It was during Sir Kenelm's confinement in Winchester house, that he composed his Observations upon Religio Medici, and his Observations on the 22d Stanza, in the ninth Canto of the second book of Spenser's Fairy Queen, — two works excellently adapted, from their nature, to show the peculiar views of the author, and the character of his mind. On his return to Paris he was welcomed among the courtly and literary circles of that metropolis, as one of their chief ornaments. He was now also in a situation to resume his studies, and the fruit of his leisure were A Treatise of the Nature of Bodies; — A Treatise declaring the Operations and Nature of Man's Soul, out of which the Immortality of reasonable Souls is evinced; — and Institutionum Peri-pateticarum libri quinque, cum Appendice Theologica de Origine Mundi. These works were published in Paris, and evince considerable powers of thought employed on the systems then in vogue. They were also not wanting in originality, but the amount of credit due to originality is not easily determined when science is so little established on the real laws of nature that every wild hypothesis and bold assertion passes for a discovery of the true principles of the universe. Of Sir Kenelm's character as a philosopher, some idea may be formed from the anecdote he relates of the sympathetic powder. According to his own account of this marvellous medicine, he learned the secret of its manufacture from a Carmelite, who had himself been taught it in the East; and the occasion on which he first proved its virtues was the following: — A Mr. Howell, in endeavouring to part two of his acquaintances, who had drawn their swords on each other, received a severe wound in the hand. The agony he suffered was extreme, and it was feared that the hurt would produce mortification. Sir Kenelm was consulted by the gentleman as to the best mode of treating the wound, and instead of recommending him any medicaments, requested him to produce any of the bandages on which the blood was remaining. Mr. Howell complied with the directions, and while he was talking with some other person in the chamber, our philosopher steeped the bandage in a basin in which he had previously dissolved "a handful of powder of vitriol." "I observed," says he, "in the meanwhile, what Mr. Howell did, who stood talking with a gentleman in a corner of my chamber, not regarding at all what I was doing; but he started suddenly, as if he had found some strange alteration in himself. I asked him what he ailed? I know not what ails me, replied he, but I find that I feel no more pain; methinks that a pleasing kind of freshness, as if a wet, cold napkin did spread over my hand, has taken away the inflammation that tormented me before. I answered, since you feel already so good an effect of my medicament, I advise you to cast away all your plasters, only keep the wound clean, and in a moderate temper between heat and cold." But the most marvellous part is yet to come. An account of the cure was immediately given to the king and the duke of Buckingham. To satisfy whose curiosity, Sir Kenelm, as he states, took the bandage after dinner "out of the water, and put it to dry before a great fire. It was scarce dry; but Mr. Howell's servant came running, that his master felt as much burning as ever he had done, if not more, for the heat was such as if his hand were betwixt coals of fire. I answered, that though that had happened at present, yet he should find ease in a short time, for I knew the reason of this accident, and I would provide accordingly, for his master should be free from that inflammation, it may be before he could possibly return unto him; but in case he found no ease, I wished him to come presently back again, if not, he might forbear coming. Thereupon he went, and at the instant I did put again the garter into the water, he found his master without any pain at all."
It may be said, however, in excuse for Sir Kenelm, that in the belief he entertained respecting the virtues of the sympathetic powder he was not more extravagant than the other philosophers of the period. Descartes himself felt assured that he had the means of preserving his life to the age of the patriarchs, and there are some things in the works of the great Bacon which show how unwillingly even the acutest reasoners of the period parted with the idea of an omnipotent philosophy. We must not, therefore, refuse to Sir Kenelm the praise he merits for industry and talent. His cotemporaries considered him as worthy of a place among the most famous philosophers, and the treatises which were written against him and his systems prove that his views were regarded as in a great measure the product of his own reasoning and inquiry.
While the parliament forces were in their full career of triumph, he visited England to make some arrangement respecting his estate; but the short period he remained here was one of trouble and affliction. After losing his eldest son, who fell while fighting among the royalists, he was himself ordered to quit the kingdom, and prohibited from returning without leave of parliament, on peril of losing both his estate and life. He therefore hastened back to France, and was thence sent by the dowager-queen of England, who had made him her chancellors into Italy. The account which the zealous historian of Oxford gives of this journey, would lead to the suspicion that Sir Kenelm was more mindful of his own interest than of the unfortunate Catholics, whose cause he pleaded. "He was," says he, "at his first coming to Rome, highly venerated by all people, as being a person, not only of a majestic port and courage, but of extraordinary parts and learning. At length growing high, and huffing his holiness, he was in a manner neglected, and especially for this reason, that having made a collection of money for the afflicted Catholics in England, he was found to be no faithful steward in that matter." The doubts which were thus entertained respecting his conduct in this matter, were not diminished by the reconciliation which he soon after formed with Cromwell; and when it was said in praise of his eloquence and manners, that he would have made himself respected in any part of the world, the Jesuits were accustomed to reply, "It is true, but then he must not have staid there above six weeks." One of the proofs adduced of his intimacy with the Protector is, that the English merchants at Calais employed him as their advocate when they desired to obtain some particular favour from the government, and there appears every reason to believe, that during a stay of some time in England he was regarded with that jealousy which generally attends a suspected person. But in France he continued to enjoy the esteem and reputation he had early possessed in that country; and both at Thoulouse and Montpelier, where he resided some time for the benefit of his health, he was the centre of a numerous literary society. Before returning to England, he visited the Low Countries, where he spent the year 1658 and part of 1659. It was probably at this time that he paid the visit to Descartes, which is mentioned by his biographers as one of the most curious particulars of his life. The great philosopher had received no intimation of his coming, and Sir Kenelm keeping his name secret, the conversation was carried on for some time without his host's discovering that he was the Englishman whose works were already so widely diffused. At length some observation was made, which Descartes eagerly fixed on, and told his visitor that he must be Sir Kenelm Digby. He added that he greatly valued the philosophical productions of his pen, and treated him with an attention which confirmed his expressions of respect.
In 1661, after another year spent in Paris, he returned to England, and was sufficiently skilful as a courtier to secure a favourable reception from the restored monarch. Though not appointed to any place in the government, he was elected one of the council of the Royal Society, then in course of formation, and, notwithstanding his suspicious connexion with Cromwell, and the active part he still took in the affairs of the Catholics, the most powerful men of the time cultivated his friendship without reserve. His house in Covent-Garden, where he spent the remainder of his days, was the constant resort of the learned and ingenious. He continued to pursue his favourite studies with ardour till the spring of 1665, when his disorder, the stone, to which he bad been subject for some years past, gained the better of his strength, and he expired on the 11th of June, the anniversary of his birth. He had raised an elegant monument over his late wife, who lay buried in Christ-church, Newgate, and his remains were deposited in the same vault. The reputation he enjoyed among his cotemporaries was soon eclipsed by that galaxy of scientific lights which appeared almost immediately after his decease; but he deserves the gratitude of posterity as one of the earliest of English scholars who devoted themselves with zeal to the inquisition of nature.