The weakness as well as the strength of ancient science lay in its perception of analogies. The mind of Lucretius was both under the influence of earlier analogical conceptions, and also shows great boldness and originality in the logical and poetical apprehension of 'those same footsteps of Nature, treading on diverse subjects or matters.' But, in common with the earlier enquirers of Greece, he trusts too implicitly to their guidance through all his daring adventure. He seems to believe that the hidden properties of things are as open to discovery through this 'lux sublustris' of the imagination, as through the 'lucida tela' of the reason. To take one prominent instance of this influence, it is remarkable how, in his explanation of our mundane system, he is both consciously and unconsciously guided by the analogy of the human body. Even Lucretius, living in the very meridian of ancient science, cannot in imagination absolutely emancipate himself from the associations of mythology. He is indeed conscious of the inconsistency of attributing life and sense to the earth: yet not only does he speak poetically of Earth being the creative mother, Aether the fructifying father of all things, but his whole conception of the creation of the world is derived from a supposed likeness between the properties of our terrestrial and celestial systems, and those of living beings. Thus we read-- Undique quandoquidem per caulas aetheris omnis Et quasi per magni circum spiracula mundi Exitus introitusque elementis redditus extat[22]. Of the growth of plants and herbage it is said-- Ut pluma atque pili primum saetaeque creantur Quadripedum membris et corpore pennipotentum, Sic nova tum tellus herbas virgultaque primum Sustulit, inde loci mortalia saecla creavit[23]. From v. 535 to 563 the power of the air in supporting the earth 'in media mundi regione' is compared with the power which the delicate vital principle has in supporting the human body. Again, the gathering together of the waters of the sea is thus represented-- Tam magis expressus salsus de corpore sudor Augebat mare manando camposque natantis[24]. And finally, though it would be easy to multiply such quotations, the striking account, at the end of the second book, of the growth and the decay of our world is drawn directly from the obvious appearances of the growth and decay of the human body; e.g.-- Quoniam nec venae perpetiuntur Quod satis est neque quantum opus est natura ministrat[25].