''The Stein children,'' Oskar Kokoschka wrote in his book My Life, ''came before me flushed from playing, clothes rumpled, the girl in a pink and white striped garden frock of the kind that parents seem to think appropriate for the occasion, the boy in the inevitable Sunday sailor suit. . . .''
In a single, defiant, painterly gesture, the Austrian artist managed to shatter most of the conventional and stilted expectations of child portraiture (conventions still vigorously adhered to, for example, in the work of most studio photographers). The brother and sister were not painted to charm or please their parents. They were not prettified or sentimentalized. They were not tidied, hair brushed, socks pulled up. Naturalness more than predominated over arrangement. Nor, at a rather deeper level, were they the innocents of an earlier period. The romantic notion of childhood as a pristine enigma either poignantly lost or to be somehow regained takes an abrupt knock from the picture of the Stein children.
The German nineteenth-century artist Philipp Otto Runge said: ''We must become children again if we wish to achieve the best.'' Kokoschka, on the other hand, seems to indicate that there is something unbelievable about that kind of naive idealism in the face of actual children.
And yet this work of 1909 is not strictly speaking anti-Romantic. It conveys, in fact, with some potency, Kokoschka's basic contention about small children, that they ''are not habituated to life as grown-ups are,'' and that they have secrets which adults just fail to grasp.
''We imagine,'' he wrote, ''that we've made ourselves clear to children when all we've done is to talk down to them. We are no more than vulgar interlopers in their kingdom of dreams - a realm in which, however childishly we behave, we share very little. Yet sometimes in the midst of all our self-deception, we are taken unawares by a moment of sharp regret at ever having become outsiders: it is the moment when a child suddenly looks at us as if we were not there.''