De la Mare described two distinct "types" of imagination ... although "aspects" might be a better term: the childlike and the boylike. It was at the border between the two that Shakespeare, Dante, and the rest of the great poets lay.

De la Mare claimed that all children fall into the category of having a childlike imagination at first, which is usually replaced at some point in their lives. In his lecture, "Rupert Brooke and the Intellectual Imagination," he argued that children ". . . are not so closely confined and bound in by their groping senses. Facts to them are the liveliest of chameleons . . . They are contemplatives, solitaries, fakirs, who sink again and again out of the noise and fever of existence and into a waking vision." Doris Ross McCrosson summarizes this passage, "Children are, in short, visionaries." This visionary view of life can be seen as either vital creativity and ingenuity, or fatal disconnection from reality (or, in a limited sense, both).

The increasing intrusions of the external world upon the mind, however, frighten the childlike imagination, which "retires like a shocked snail into its shell." From then onward the boyish imagination flourishes, the "intellectual, analytical type."

By adulthood (de la Mare proposed), the childlike imagination has either retreated for ever or grown bold enough to face the real world. Thus emerge the two extremes of the spectrum of adult minds: the mind molded by the boylike is "logical" and "deductive". That shaped by the childlike becomes "intuitive, inductive." De la Mare's summary of this distinction is, "The one knows that beauty is truth, the other reveals that truth is beauty." Another way he puts it is that the visionary's source of poetry is within, while the intellectual's sources are without ... external ... in "action, knowledge of things, and experience," as McCrosson puts it. De la Mare hastens to add that this does not make the intellectual's poetry any less good, but it is clear where his own preference lies.

A note to avoid confusion: The term "imagination" in the lecture "Rupert Brooke and the Intellectual Imagination" is used to refer to both the intellectual and the visionary. To simplify and clarify his language, de la Mare generally used the more conventional "reason" and "imagination" when discussing the same idea elsewhere.

Writer Joan Aiken cites some of his short stories such as Almond Trees and Snow Mountains for their sometimes unexplained quality, which she also employs in her own work.

Come Hither was an anthology, edited by De la Mare, mostly of poetry with some prose. It has a frame story, and can be read on several levels. It was first published in 1923, and was a success; further editions followed. Alongside the children's literature aspect, it also provides a selection of the leading Georgian poets (from de la Mare's perspective). It is arguably also the best account of their 'hinterland', documenting thematic concerns and a selection of their predecessors.

De la Mare was also a significant writer of ghost stories. John Clute comments that "in his long career, De la Mare seems to have published about 100 stories, of which about eighty-five have been collected. At least forty of these have supernatural content". Many of De la Mare's ghost stories can be found in the collections Eight Tales, The Riddle and Other Stories, The Connoisseur and Other Stories, On the Edge and The Wind Blows Over. His complete short stories have now been published in three volumes issued by Giles de la Mare Publishers, London. De la Mare also wrote two supernatural novels, Henry Brocken (1904) andThe Return (1910) and for children, The Three Mulla Mulgars (1910, AKA The Three Royal Monkeys), described bycritic Brian Stableford as a "classic animal fantasy".

Walter John de la Mare was born to James Edward de la Mare, a clerk at the bank of England, and Lucy Sophia Browning (James' second wife), daughter of Scottish naval surgeon & author Dr Colin Arrott Browning. The assertion that Lucy was related to poet Robert Browning has been found to be incorrect. He had two brothers, Francis Arthur Edward and James Herbert ('Bert'), and four sisters Florence Mary, Constance Eliza, Ethel (who died in infancy), and Ada Mary ('Poppy'). De la Mare was known as Jack by his family and friends as he hated the name Walter.

In 1892, De la Mare joined the Esperanza Amateur Dramatics Club, where he met and fell in love with Elfrida (Elfie) Ingpen, the leading lady. Elfie was ten years older than De la Mare. On August 4, 1899 De la Mare and Elfie, who was by then pregnant, were married. They went on to have 4 children — Richard Herbert Ingpen ('Dick'), Colin, Florence and Lucy Elfrida ('Jinnie') de la Mare. In 1940 Elfie was diagnosed with Parkinson's disease and spent the rest of her life as an invalid, eventually dying in 1943. From 1940 until his death, De la Mare lived in Montpelier Row, Twickenham, the same street where Alfred Tennyson, 1st Baron Tennyson had lived a century earlier. In 1947 he suffered from coronary thrombosis and died of another in 1956.

Novels

• Henry Brocken (1904)
• The Three Mulla Mulgars (1910) ... also published as The Three Royal Monkeys (children's novel)
• The Return (1910; revised edition 1922; second revised edition 1945)
• Memoirs of a Midget (1921)

Short story collections

• The Riddle and Other Stories (1923)
• Ding Dong Bell (1924)
• Broomsticks and Other Tales (1925)(children's stories)
• The Connoisseur and Other Stories (1926)
• On the Edge (1930)
• The Lord Fish (1930)(children's stories)
• The Walter de la Mare Omnibus (1933)
• The Wind Blows Over (1936)
• The Nap and Other Stories (1936)
• Stories, Essays and Poems (1938)
• The Best Stories of Walter de la Mare (1942)
• Collected Stories for Children (1947)
• A Beginning and Other Stories (1955)
• Eight Tales (1971)
• Walter de la Mare, Short Stories 1895—1926 (1996), Walter de la Mare, Short Stories 1927—1956 (2000), and Walter de la Mare, Short Stories for Children (2006) (Complete edition, ed. Giles de la Mare)

Poetry collections

• Songs of Childhood (1902)
• The Listeners (1912)
• Peacock Pie (1913)
• The Marionettes (1918)
• O Lovely England (1952)
• Walter de la Mare, The Complete Poems ed. Giles de la Mare (1969)

Plays

• Crossings: A Fairy Play (1921)

Nonfiction

• Some Women Novelists of the 'Seventies (1929)
• Desert Islands and Robinson Crusoe (1930)

Anthologies edited

• Come Hither (1923; new and revised edition, 1928; third edition, reset and printed from new plates, 1957)
• Desert Islands, and Robinson Crusoe (1930)
• Early one Morning, in the Spring. Chapters on children and on childhood as it is revealed in particular in early memories and in early writings. (1935)
• Behold, This Dreamer! Of reverie, night, sleep, dream, love-dreams, nightmare, death, the unconscious, the imagination, divination, the artist, and kindred subjects. (1939)
• Love (1943)

De la Mare's play Crossings has an important role in Robertson Davies' novel The Manticore. In 1944, when the protagonist David Staunton is sixteen, de la Mare's play is produced by the pupils of his sister's school in Toronto, Canada. Staunton falls deeply in love with the girl playing the main role — a first love which would have a profound effect on the rest of his life.