The lines on "gentle Spenser, Fancy's pleasing Son; | [who] pour'd his Song | O'er all the Mazes of enchanted Ground" were added to Summer in the 1744 edition of The Seasons; they are included among the commendatory verses in Todd's Works of Spenser (1805).
The phrase "enchanted ground," which James Thomson popularized, had recently been used in the 1742 translation of Joseph Trapp's Praelectiones Poeticae: "our Countryman Spencer is still more remarkably guilty, who treads almost perpetually upon enchanted Ground, and the greatest Part of whose Characters are Fairies, Ghosts, Magicians and Giants. He is all over Allegory, pursues not one Action but several." Thomson's inversion of Trapp's sentiment set the tone for later romantic criticism of Spenser.
Samuel Johnson: "These poems, with which I was acquainted at their first appearance, I have since found altered and enlarged by subsequent revisals, as the author supposed his judgement to grow more exact, and as books or conversation extended his knowledge and opened his prospects. They are, I think, improved in general; yet I know not whether they have not lost part of what Temple calls their race, a word which, applied to wines, in its primitive sense, means the flavour of the soil" Lives of the English Poets (1779-81); ed. Hill (1905) 3:300-01.
William Lyon Phelps: "How early Thomson began to admire Spenser is hard to say. It is an interesting fact that the allusion to Spenser in The Seasons did not appear in the first edition (1730), but was inserted later.... Perhaps this was inserted after Thomson had begun to have in mind The Castle of Indolence. We know that he had this intention as early as 1733 or 1734, for he writes in 1748, 'After fourteen or fifteen years, The Castle of Indolence comes abroad in a fortnight'" Beginnings of the English Romantic Movement (1893) 74.
Let NEWTON, pure intelligence, whom GOD
To Mortals lent, to trace his boundless Works
From Laws sublimely simple, speak thy Fame
In all Philosophy. For lofty Sense,
Creative Fancy, and Inspection keen
Thro' the deep Windings of the human Heart,
Is not wild SHAKESPEAR thine and Nature's Boast?
Is not each great, each amiable Muse
Of Classic Ages in thy MILTON met?
A Genius universal as his Theme,
Astonishing as Chaos, as the Bloom
Of blowing Eden fair, as Heaven sublime.
Nor shall my Verse, that elder Bard forget,
The gentle SPENSER, Fancy's pleasing Son;
Who, like a copious River, pour'd his Song
O'er all the Mazes of enchanted Ground:
Nor Thee, his antient Master, laughing Sage,
CHAUCER, whose native Manners-painting Verse
Well-moraliz'd, shines thro' the Gothic cloud
Of Time and Language o'er thy Genius thrown. . . .