Yeats is the indispensable bridge between Romanticism and Modernism, his early Celtic twilight giving way to the hard, bitter, visionary poetry of The Tower and The Winding Stair. "The Second Coming," "Leda and the Swan," "Sailing to Byzantium," "Among School Children": they sound unlike each other and unlike anything else. His "gyre" cosmology (elaborated in A Vision) is mystical nonsense that generated magnificent poetry. Nobel Prize 1923.

The case for it, the case against, and the rest of the canon open with Pro.