This consummate drawing was for a small part of Raphael's last painting, ''The Transfiguration,'' which he left unfinished - an altarpiece commissioned in Rome in 1517. At that time the artist was entrenched in various archaeological and architectural projects; painting was no longer his main concern. A little paradoxically, it is to this fact that we owe the superb quality of the black chalk drawing from Oxford, for if he had been able to give more time to actually painting ''The Transfiguration'' (rather than having to entrust much of it to his workshop) Raphael would not have felt the need to carry his preparatory studies for it to this degree of completeness and finality of expression.
''Studies of the Heads of two Apostles and of their Hands'' has with justice been valued as one of the finest examples of draughtsmanship from the mature hand of one of the world's most accomplished draughtsmen. Fully realized form, magically coherent, is played over by the subtlest lights and shadows, and these in turn serve to heighten the attitudes of thought Raphael wanted to convey in the intent faces of John and Peter. The whole painting, in fact, has two contrasting subjects: the transfiguration itself, when Jesus took three of his apostles ''into a high mountain apart'' to be ''transfigured before them: and his face did shine as the sun, and his raiment was white as the light,'' and Moses and Elias were seen talking with him. This is naturally enough in the upper regions of the picture. Below is enacted the scene which follows it in Matthew's gospel when the disciples were confronted with a boy who was ''lunatick, and sore vexed.'' They failed to heal him. But Jesus ''cured him from that very hour.'' Raphael makes interesting visual links between the two events, suggesting perhaps that the solution to the boy's difficulty could be found (as indeed it was) in the exalted spirituality represented by the transfiguration.
The ''John'' and ''Peter'' of the Oxford drawing are in the lower part of the picture (though they are also, of course, present in the upper part), and the artist portrays in their faces and hands questioning and doubt, concern, and a gentle, longing compassion. Later they were to ask Jesus why they had been unable to heal the boy.
It is remarkable in a drawing made to express uncertainties, that its own confidence and sureness of touch marvellously overrides its subject. Throughout his career Raphael displayed a considerable capacity for thoroughness. Where another artist might have been satisfied with a carefully organized composition, this utterly painstaking one, (eager always to assimilate the originality of admired contemporaries like Michelangelo and Leonardo) persistently adjusted and altered, pondered and explored fresh possibilities in his drawings. He subjected himself to a kind of relentless questioning - evident in the large number of his drawings that have survived, from first quick notions to the most complete realizations - aiming all the time at a balance and harmony, a classical poise, which has been neatly described by Ernst Gombrich as looking ''as if it could not be otherwise, and as if it had so existed from the beginning of time.''
The ''Two Apostles'' drawing certainly has such a quality. This is all the more impressive because, in essence, it was drawn for purely practical reasons as a detailed and precise instruction to his assistants just before they began to paint. In his early works Raphael had made similar last minute drawings - Oskar Fischel named them ''auxiliary cartoons'' - as instructions to himself. This was possibly because he still felt more at ease drawing than painting. But after this he apparently felt no need of such finished preparations, and painted with a more direct confidence: at least, no auxiliary cartoons have survived later than those connected with his early works - until they reappeared in strength for his final painting, ''The Transfiguration.'' On this occasion he must have resorted to the practice because he wanted hurriedly to give his pupils the greatest possible indication of his intentions. The result was a number of drawings of similar quality to the ''Two Apostles,'' though none finer. Few masters of drawing have rivalled their infusion of the ideal and ennobled into the realistically observed, or the wholesome comprehensiveness of the contours around their forms, or the unity of their solid strength with the most tender nuances of tone. They seem simultaneously to be as impalpable as air and yet as definite as antique marble.