In the translation Poussin read, that picture is a meditation on three themes—the art of painting, the beauty of nature, and the character of human destiny—the very subjects that preoccupied Poussin throughout his career, and of which he sought to give final expression in this last series. The full significance of such profound works has been discussed by scholars and critics ever since their making. What is not open to dispute is the fixity of attention and the seriousness of purpose with which he completed these sublime paintings. Joshua Reynolds, William Hazlitt, and Kenneth Clark have each compared Poussin with the epic grandeur of Milton, and looking at these works, I am reminded of lines from the conclusion of Il Penseroso, which was written in the 1630s:
And may at last my weary age
Find out the peacefull hermitage,
Where I may sit and rightly spell
Of every Star that heav’n doth shew,
And every Herb that sips the dew;
Till old experience do attain
To something like Prophetic strain.
Like the narrator of the poem, Poussin contemplated human character and natural order in search of the essential and the eternal.
more from the NYRB here.