When we have crossed the threshold of the Propylæa, and have visited the Parthenon, the Erecthæum, and the temple of the Wingless Victory; when we have seen all Greece become covered with monuments of architecture and sculpture, which, without rivalling those of Athens in purity of line or finesse of execution, bear the impress of the same style and the same taste; when we have seen Praxiteles and Scopas succeed to Phidias and Polycletus, will it not cost us a struggle to quit the scene of so many wonders and conclude our voyage? If we leave the Athens of Cimon, of Pericles, and Lycurgus, for the pompous capitals of the heirs of Alexander; if we cross the sea to visit Veii and Clusium, to describe the Etruscan cemeteries with the fantastic magnificence of their decoration; if at last we find ourselves in imperial Rome, among its basilicas, its baths, its amphitheatres, and all the sumptuous evidence of its luxury, we shall now and again turn our eyes with regret to what we have left behind; and, although we shall endeavour to comprehend and to judge with the liberality and largeness of taste and sympathy which is the honour of contemporary criticism, we shall sometimes sigh for that ideal of pure and sovereign beauty which we adored in Greece; and shall feel, now and again, the nostalgia of the exile. IV. In this sketch of our plan, we have reserved no place for the art which is called _prehistoric_, the art of the caverns and the lake dwellings. This omission may surprise some of our readers, and we therefore beg to submit for their consideration the reasons which, after grave reflection, have induced us to refrain from retracing the first steps of human industry, from describing the first manifestations of the plastic instinct of mankind. We are actuated by neither indifference nor disdain. We fully appreciate the importance of such researches, and of the results to which they have led. No sooner had it entered into the mind of man to look for and collect the humble remains upon which so many centuries had looked with indifference, than they were found almost everywhere, thickly dispersed near the surface of the earth, heaped among the bones of deer in the grottoes for which men and animals had once contended, buried in peat marshes and sandy shores, sometimes even sprinkled upon the surface of the fields and country roads. Pieces of flint, bone, or horn, fashioned into instruments of the chase, into fishhooks, and domestic utensils; shells, perforated teeth, amber balls which were once strung upon necklaces and bracelets; fragments of rough tissue and of skin garments; seeds and carbonized fruits; earthen vessels made by hand and dried in the sun or simply in the open air. In some of the cave dwellings, bones and pieces of horn have been found upon which the figures of animals are carved with a truth and spirit which allow their species to be at once and certainly recognized.