257. And thus, as we follow our proposed examination of the arts of the Christian centuries, our understanding of their work will be absolutely limited by the degree of our sympathy with the religion which our fathers have bequeathed to us. You cannot interpret classic marbles without knowing and loving your Pindar and Æschylus, neither can you interpret Christian pictures without knowing and loving your Isaiah and Matthew. And I shall have continually to examine texts of the one as I would verses of the other; nor must you retract yourselves from the labour in suspicion that I desire to betray your scepticism, or undermine your positivism, because I recommend to you the accurate study of books which have hitherto been the light of the world. 258. The change, then, in the minds of their readers at this date, which rendered it possible for them to comprehend the full purport of Christianity, was in the rise of the new desire for equity and rest, amidst what had hitherto been mere lust for spoil, and joy in battle. The necessity for justice was felt in the now extending commerce; the desire of rest in the now pleasant and fitly furnished habitation; and the energy which formerly could only be satisfied in strife, now found enough both of provocation and antagonism in the invention of art, and the forces of nature. I have in this course of lectures endeavoured to fasten your attention on the Florentine Revolution of 1250, because its date is so easily memorable, and it involves the principles of every subsequent one, so as to lay at once the foundations of whatever greatness Florence afterwards achieved by her mercantile and civic power. But I must not close even this slight sketch of the central history of Val d'Aruo without requesting you, as you find time, to associate in your minds, with this first revolution, the effects of two which followed it, being indeed necessary parts of it, in the latter half of the century. 259. Remember then that the first, in 1250, is embryonic; and the significance of it is simply the establishment of order, and justice against violence and iniquity. It is equally against the power of knights and priests, so far as either are unjust,--not otherwise.