Giorgio Vasari, that informative (sometimes overinformative) biographer of the Italian Renaissance, records as one of Leonardo da Vinci's engaging characteristics such a fondness for animals that he would even buy caged birds to set them free. Surprisingly, however, there doesn't exist today very much evidence that Leonardo actually studied more than a handful of creatures, other than horses and cats, and those he did draw are mostly quite ordinary. He was not, like Durer, a man to travel miles to see a strange beast.
At the end of the 1470s, when he was still a young artist working in Florence and still very much part of the milieu and traditions of the art of that city, he began work on two Virgin Marys. There is speculation, of course, as to which known paintings by him were the final result of this work.
One almost certainly was the so-called ''Benois Madonna,'' located in the Hermitage in Leningrad: a very young and lighthearted girl handing a flower to her rather plump baby. (''Plump'' is kind to the baby: Kenneth Clark doesn't hesitate to describe it as ''monstrous.'')
In his book on Leonardo, Clark uses the ''Benois Madonna'' to show the difference between the academic Leonardo, whose paintings were sometimes marred by a need to carry them to a state of overworked finish, and the spontaneous Leonardo, with his ''matchless quickness of vision.'' The latter clearly applied to the British Museum drawing ''The Virgin and Child With a Cat,'' which may, in fact, have been an idea he explored and then abandoned in his preparation process for the ''Benois Madonna.'' The arched frame, fashionable in Florentine paintings at that date, the window to the right of the Madonna's head, and her own pose are not wildly dissimilar to those in the painting, though the child is quite different.
The many Leonardo drawings that exist showing children playing with a cat indicate a keen interest in the theme. They are wonderfully observed and ring true to the way young children tend to cuddle a pet animal greedily one minute and innocently torment it the next, as if it were an inanimate toy. The various reactions of the cats in these drawings to this treatment is hurriedly and brilliantly depicted.
One wonders why Leonardo (assuming that the evidence and theorizing are correct) did not pursue the idea of a Virgin and Child with a cat any further. Perhaps he felt in the end that this carried the humanization of this sacred subject too far. Mid 15th-century Florentine sculptors and painters had already been emphasizing the human rather than the divine in this subject, often with happy and charming results, and Leonardo, following suit, was also seeing it as essentially in terms of a young girl and her baby.
But the introduction of the cat made the child respond and behave in ways that obviously fascinated the artist privately but that might not have been considered suitable in a more public or devotional context. After all, the cat looks as if it would gladly escape the too affectionate clutches of the baby, and the baby is equally intent on preventing it from doing so.
It is fortunate that these drawings have survived. This one, even though it is a melee of contradictory decisions and revisions, isamong the most delightful of the group. The contrast between the girl's gentle hold on the child, and the child's less restrained embrace of the poor animal, is the germ of an idea Leonardo transformed almost 30 years later in the painting ''Virgin and Child and Ste. Anne,'' now in the Louvre. Here, the relationship moves across the picture as the mother reaches for the child and the child reaches for a lamb, fondling its ears.
But the lamb is a traditional symbol of Christian innocence and sacrifice, a cat is not. It tells us much about the deep consistency of Leonardo's vision that the youthful, freely reined sketches and tryouts of his early development could come into the belated service of a profoundly complex work of his maturity. Sweetness and momentary playfulness are turned into a consummately tender and monumental image of wise motherhood, and, far more difficult to picture, wise childhood. It was this demand - that the Christ child should somehow be an ordinary baby and at the same time an authoritative figure - which tested painters of the Virgin and Child. They tended to swing one way or the other. One of Leonardo's remarkable achievements is his gradual development of a highly individual balance of holy significance and quiet humanity in his increasingly heroic treatments of the subject.