It is commonly, but wrongfully, supposed that Rembrandt used his broadest manner in painting commissioned portraits. The number of his portraits known to exist is about 450, of which fifty-five are representations of himself, and fifty-four of members of his household, or relatives. There are, further, more than seventy studies of old men and women, and thirty of younger men. The balance are commissioned portraits or groups. This last section includes none at all of his palette knife pictures, and not more than two or three which are executed with his heaviest brushes. Generally his work broadened in his later period, but up to the end of his life his more important works were often painted in a comparatively fine manner, though the handling was less careful and close.[a] The broadest style of the artist is rarely exhibited except in his studies and family portraits. Further it is extremely unlikely that a palette-knife picture would have been accepted in Holland during Rembrandt's time as a serious work in portraiture. [a] See among works dating after 1660, The Syndics of the Drapers, Portrait of a Young Man, Wachtmeister Collection; Lady with a Dog, Colmar Museum; and Portrait of a Young Man, late Beit Collection. NOTE 9. PAGE 22 Darwin pointed out the permanent character of the changes in the nerves, though he submitted another demonstration[a]: That some physical change is produced in the nerve cells or nerves which are habitually used can hardly be doubted, for otherwise it is impossible to understand how the tendency to certain acquired movements is inherited. [a] _The Expression of the Emotions in Man and Animals._ NOTE 10. PAGE 23 Reynolds evidently had little faith in original genius. Addressing Royal Academy students, he said[a]: You must have no dependence on your own genius. If you have great talents, industry will improve them; if you have but moderate abilities, industry will supply the deficiency. Nothing is denied to well-directed labour; nothing is to be obtained without it.... I will venture to assert that assiduity unabated by difficulty, and a disposition eagerly directed to the object of its pursuit, will produce effects similar to those which some call the result of natural powers. On another occasion Reynolds observed of Michelangelo[b]: He appears not to have had the least conception that his art was to be acquired by any other means than great labour; and yet he of all men that ever lived, might make the greatest pretensions to the efficacy of native genius and inspiration. Gibbon said that Reynolds agreed with Dr. Johnson in denying all original genius, any natural propensity of the mind to one art or science rather than another.[c] Hogarth also agreed with Reynolds, for he describes genius as "nothing but labour and diligence."