There is a freshness, a vivacity, a zeal, a sincerity, a brightness of interest in his subject, which are perhaps unique in the whole history of criticism. He flings himself into the task with the perfection of natural abandonment to a joyous and delightful subject. His whole personality is engaged in a work that has all the air of being overflowing pleasure, and his pleasure is contagious. His criticism awakens the imagination of the reader. Not only do we see the picture; we hear Diderot's own voice in ecstasies of praise and storms of boisterous wrath. There is such mass in his criticism; so little of the mincing and niggling of the small virtuoso. In facility of expression, in animation, in fecundity of mood, in fine improvisation, these pieces are truly incomparable. There is such an _impetus animi et quaedam artis libido_. Some of the charm and freedom may be due to the important circumstance that he was not writing for the public. He was not exposed to the reaction of a large unknown audience upon style; hence the absence of all the stiffness of literary pose. But the positive conditions of such success lay in the resources of Diderot's own character. The sceptic, the dogmatist, the dialectician, and the other personages of a heterogeneous philosophy who existed in Diderot's head, all disappear or fall back into a secondary place, and he surrenders himself with a curious freedom to such imaginative beauty as contemporary art provided for him. Diderot was perhaps the one writer of the time who was capable on occasion of rising above the strong prevailing spirit of the time; capable of forgetting for a season the passion of the great philosophical and ecclesiastical battle. No one save Diderot could have been moved by sight of a picture to such an avowal as this: "Absurd rigorists do not know the effect of external ceremonies on the people; they can never have seen the enthusiasm of the multitude at the procession of the _Fete Dieu_, an enthusiasm that sometimes gains even me. I have never seen that long file of priests in their vestments; those young acolytes clad in their white robes, with broad blue sashes engirdling their waists, and casting flowers on the ground before the Holy Sacrament; the crowd as it goes before and follows after them hushed in religious silence, and so many with their faces bent reverently to the ground; I have never heard that grave and pathetic chant, as it is led by the priests and fervently responded to by an infinity of voices of men, of women, of girls, of little children, without my inmost heart being stirred, and tears coming into my eyes. There is in it something, I know not what, that is grand, solemn, sombre, and mournful."