He had been brought up in a brewing establishment, at Edinburgh, but had early shewn an enthusiastic love for poetry. He submitted several of his early poems, and among them Providence, to Lyttelton's supervision. Lyttelton seems to have treated him with the greatest kindness, both by letter, and in a personal interview, when having been surety for an insolvent friend, who became bankrupt, he came to London in 1764. He had previously written to Lyttelton, under the assumed name of William More, describing himself "as a young man friendless and unknown," begging to be allowed to dedicate to him a second edition of Providence, and that an answer might be sent to him at a Coffee House in Holborn. Before the answer could arrive there, the utter derangement of his affairs had driven him from his home, and he had reached London in the greatest distress. While in this perplexity, he received a cheering letter from Lyttelton, warmly commending his genius, but containing several criticisms on his poems, urging him to acquire greater harmony of versification, to take care that his diction did not "loiter into prose," or become harsh by new phrases or words unauthorised by the usage of good authors. Mickle took in good part this and other criticisms, from which he always professed to have derived considerable advantage. When he thought of seeking his fortune in Jamaica, Lyttelton gave him a letter of recommendation to his brother, who was at that time governor of the island.