CLASSIFICATION, and the distinguishing of styles and relationship, is essential to literary criticism, but some writers are members of a class that contains no other member. Such troublemakers, who won't quite fit in anywhere, tend to get left out of the textbooks and ignored in the discussions. Critical neglect may be over-compensated by uncritical praise from reader-devotees, which gives the critics ground to gibe at the "cultists," whose praise then grows shriller.

The major fantasists are all mavericks, and all of them, including Carroll and Tolkien, have traveled at least part of this descending gyre of neglect-defense-contempt-adulation. So have such great unclassifiable novels as Kim and Finnegans Wake. Though American Lit. people ought to be used to mavericks, they don't seem to be able to lay a rope on Austin Tappan Wright, the author of the Utopian fantasy Islandia. An illustrious name in the egregious non-company of those who don't belong is that of Mervyn Peake; and now, possibly to the annoyance of the critics, certainly to the delight of his readers, Peake's Progress has appeared to exhibit the maverick genius in all his superb gaits and paces -- storyteller, playwright, illustrator.

If one has read no Mervyn Peake, the first of his books to read surely is Titus Groan, and the second Gormenghast. The third book of this great baroque trilogy, written in the terrible shadow of the illness that killed the author, is not the place to start. Some of the minor pieces and juvenilia in Peake's Progress will best please those who already love the artist; but it is full of pleasures, and the unwary dipper-in might well get caught -- by Captain Slaughterboard, perhaps, or a lurking Figure of Speech -- and emerge only to go in hot search of the trilogy.

A great debt of gratitude is owing to Maeve Gilmore, the artist's widow, for the hard and delicate task she has performed in gathering these scattered pieces of prose, verse, and drawing from the author's whole life, and to John Watney (author of a fine biography of Peake) for his sensitive introduction. My only disappointment with the book is that it is not a selection from the very best work Peake did. To one who has not read the novels or seen Peake's magnificent illustrations to Treasure Island, The Rime of the Ancient Mariner, Alice in Wonderland, the narrative pieces and drawings in this volume will give an idea of his versatility and marvelous originality, but not a full realization of his solid and enduring achievement. But the poetry in Peake's Progress is another matter. It has no right -- no right at all To soar above the orchard wall, With chilbains on its knees.

In this sort of thing Peake belongs firmly to a classifiable tradition -- a maverick tradition, of course: English nonsense verse, that maddest flower of Albion. He was a master of nonsense to equal Edward Lear.

His play The Wit to Woo, here included, is in verse, which lends its Wildean capers a singular and batty beauty: "PERCY (bursting out of cupboard door ): 'No, no, no! I cannot breathe in there -- the mothballs, Kite! Ah, let me gulp a little air again -- A little air -- a little of that space That gentle Einstein curved for our amusement. . . .'"

Wit, style, humor, daring are never common qualities; Peake has them all. But the treasure of Peake's Progress is several serious poems of extraordinary power and brilliance -- chief among them the narrative Rhyme of the Flying Bomb. A conscious heir of Coleridge and a contemporary of Dylan Thomas wrote this poem; hard to classify he may be, but a critic who ignores Mervyn Peake henceforth may be accused of ignorance. The poem is heartbreakingly and unforgettably illustrated by the man who wrote it -- 12 years after, when he could not hold the pen for more than a few moments at a time, and had to be reminded what he was drawing.

In those 20 pages alone the book earns permanence. There is also the strange Reverie of Bone, and a selection of love poems and war poems. London, 1941 ends with these lines: Across a world of sudden fear and firelight She towers erect, the great stones at her throat Her rusted ribs like railings round her heart; A figure of dry wound -- of winter wounds -- O mother of wounds; half masonry, half pain.

I know no other poems so fit to stand with Henry Moore's drawings of London in the Blitz. The clear, sure line of the draftsman expresses and contains all Peake's extravagance of passion and compassion.