There is, nevertheless, a third order of causes, for, with the forces within and without, there is the work these have already produced together, which work itself contributes towards producing the ensuing work; beside the permanent impulsion and the given environment there is the acquired momentum. When national character and surrounding circumstances operate it is not on a _tabula rasa_, but on one already bearing imprints. According as this _tabula_ is taken at one or at another moment so is the imprint different, and this suffices to render the total effect different. Consider, for example, two moments of a literature or of an art, French tragedy under Corneille and under Voltaire, and Greek drama under Æschylus and under Euripides, Latin poetry under Lucretius and under Claudian, and Italian painting under Da Vinci and under Guido. Assuredly, there is no change of general conception at either of these two extreme points; ever the same human type must be portrayed or represented in action; the cast of the verse, the dramatic structure, the physical form have all persisted. But there is this among these differences, that one of the artists is a precursor and the other a successor, that the first one has no model and the second one has a model; that the former sees things face to face, and that the latter sees them through the intermediation of the former, that many departments of art have become more perfect, that the simplicity and grandeur of the impression have diminished, that what is pleasing and refined in form has augmented--in short, that the first work has determined the second. In this respect, it is with a people as with a plant; the same sap at the same temperature and in the same soil produces, at different stages of its successive elaborations, different developments, buds, flowers, fruits, and seeds, in such a way that the condition of the following is always that of the preceding and is born of its death. Now, if you no longer regard a brief moment, as above, but one of those grand periods of development which embraces one or many centuries like the Middle Ages, or our last classic period, the conclusion is the same. A certain dominating conception has prevailed throughout; mankind, during two hundred years, during five hundred years, have represented to themselves a certain ideal figure of man, in mediæval times the knight and the monk, in our classic period the courtier and refined talker; this creative and universal conception has monopolized the entire field of action and thought, and, after spreading its involuntarily systematic works over the world, it languished and then died out, and now a new idea has arisen, destined to a like domination and to equally multiplied creations. Note here that the latter depends in part on the former, and that it is the former, which, combining its effect with those of national genius and surrounding circumstances, will impose their bent and their direction on new-born things.