In conclusion, we will give a slight sketch of the successive phases in the development of Christian art within the limits of the first three centuries; for, thanks to De Rossi’s almost microscopic examination of every accessible corner of subterranean Rome, even this is now possible. As each of these phases was derived from its predecessor by a natural sequence of ideas, it is not pretended that they are separated from one another by strict chronological boundaries which are never transgressed; yet the characteristics of the several periods are, in the main, sufficiently distinct to allow of their being followed as safe guides in determining, at least approximately, the age of any particular class, or even individual specimen of ornamentation. We have already seen that primitive Christian art sprung out of an alliance of ancient forms with new ideas; in its outward physiognomy it proceeded directly, in point of style and method of execution, from the school of Pagan decorative art, but it was animated by a new life; and therefore it began at once to create a pictorial cycle for itself, taken partly from historical and partly from allegorical materials. At first the allegorical element greatly predominated. The fish and the anchor, the lamb and the dove, the shepherd and the fisherman, may be named as the most prominent examples; and all these during the first, or, as it has been styled, the hieroglyphic or ideographic period of Christian art, were characterised by the utmost simplicity. The principal figure usually stood alone; the fisherman is catching a fish, or the shepherd is carrying a sheep upon his shoulders, and nothing more.