The combination of flat painted surfaces and unexpected objects in this work, made in the year of Surrealism's founding, extends the strategy of collage that Ernst and fellow Dada artists had employed and marks what he described as "a kind of farewell to a technique." A red wooden gate affixed to the painted surface opens onto a deceptively pastoral scene dominated by blue sky. One female figure brandishes a small knife as though fending off the unassuming nightingale at left; another falls limp in a swoon; a man who lights atop the roof carries off a third, his hand outstretched to grab the knob fastened to the old-fashioned frame. Ernst gave two autobiographical references for the nightingale: the death of his sister in 1897 and a fevered hallucination he experienced in which the wood grain on a panel near his bed took on "successively the aspect of an eye, a nose, a bird's head, a menacing nightingale, a spinning top, and so on."
In Two Children Are Threatened by a Nightingale, a girl, frightened by the bird's flight (birds appear often in Ernst's work), brandishes a knife; another faints away. A man carrying a baby balances on the roof of a hut, which, like the work's gate (which makes sense in the picture) and knob (which does not), is a three–dimensional supplement to the canvas. This combination of unlike elements, flat and volumetric, extends the collage technique, which Ernst cherished for its "systematic displacement." "He who speaks of collage," the artist believed, "speaks of the irrational." But even if the scene were entirely a painted illusion, it would have a hallucinatory unreality, and indeed Ernst linked his work of this period to childhood memories and dreams.
Ernst was one of many artists who emerged from service in World War I deeply alienated from the conventional values of his European world. In truth, his alienation predated the war; he would later describe himself when young as avoiding "any studies which might degenerate into bread winning," preferring "those considered futile by his professors—predominantly painting. Other futile pursuits: reading seditious philosophers and unorthodox poetry." The war years, however, focused Ernst's revolt and put him in contact with kindred spirits in the Dada movement. He later became a leader in the emergence of Surrealism.
from The Museum of Modern Art , MoMA Highlights, New York: The Museum of Modern Art, revised 2004, originally published 1999, p. 105
It was Max Ernst, in 1924, who best fulfilled the Surrealist's mandate. Ernst did it above all in the construction called Two Children Are Threatened by a Nightingale, which starts from one of those instincts of irrational panic which we suppress in our waking lives. Only in dreams can a diminutive songbird scare the daylights out of us; only in dreams can the button of an alarm bell swell to the size of a beach ball and yet remain just out of our reach. Two Children incorporates elements from traditional European painting: perspectives that give an illusion of depth, a subtly atmospheric sky, formalized poses that come straight from the Old Masters, a distant architecture of dome and tower and triumphal arch. But it also breaks out of the frame, in literal terms: the alarm or doorbell, the swinging gate on its hinge and the blind-walled house are three-dimensional constructions, physical objects in the real world. We are both in, and out of, painting; in, and out of, art; in and out of, a world subject to rational interpretation. Where traditional painting subdues disbelief by presenting us with a world unified on its own terms, Max Ernst in the Two Children breaks the contract over and over again. We have reason to disbelieve the plight of his two children. Implausible in itself, it is set out in terms which eddy between those of fine art and those of the toyshop. Nothing "makes sense" in the picture. Yet the total experience is undeniably meaningful; Ernst has re-created a sensation painfully familiar to us from our dreams but never before quite recaptured in art—that of total disorientation in a world where nothing keeps to its expected scale or fulfills its expected function.
from John Russell, The Meanings of Modern Art, New York: The Museum of Modern Art, 1981, p. 206