MIRO, like Picasso, was a graphic artist as much as he was a painter, not merely a painter who also drew and engraved. His output was immense and inevitably it was variable, but he had exacting technical standards and was always a careful craftsman. He was also adventurous in the various graphic media he worked in, exploiting them for new effects and constantly reaching beyond himself.

The exhibition in the National Gallery draws heavily on his work of the 1960s, though there is a smattering of earlier pieces to show his development. Miro was, of course, strongly influenced by Klee and by Picasso, but as he aged he moved away from Klee's linear, rather precious style and became increasingly free and improvisational, almost brash. It is no secret that post war American painting made a strong impact on him, but it is arguable that he would have found his own way to Abstract Expressionism in any case (there were plenty of precedents for it in the School of Paris). Also, the New York School, in turn, owed him an early debt, which it never denied.

Miro had an early tendency - to be whimsical and "cute", but this virtually vanished as a darker, more visceral quality grew stronger. He also stepped up in scale, which was a definite, gain after the "tight" quality of the early work. A mood of sinister playfulness becomes evident, violence and hallucination are seldom very far away, large areas of black stamp themselves over other colours, there is a sense of brooding myth and spiritual turbulence. The legacy of Spanish Baroque is there, too, as well as that of Surrealism, but neither of these traditions ever rejected wit or humour, and Miro was well endowed with both.

L'Oiseau de Nuit of 1962 has a vein of dark, velvety, nocturnal poetry comparable to the best French poets of the period, most of whom Miro knew well personally. But the real quantum leap happened in the early 1970s, and just inside the entrance to the National Gallery exhibition there is a virtual triptych of large engravings which show the boldness, starkness and almost tragic quality of his "third period" - Lovers of the early Miro may not have cared for the late one, but like his fellow Catalan, Picasso, he did not sit and wait for his admirers to catch up.