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.[398] 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.[399] 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.[400] As a necessary result of a system of natural philosophy based on assumptions, largely illustrated indeed, but not corroborated by the observation of phenomena, with no verification of experiment or ascertainment of special laws, there is throughout the poem the utmost hardihood of assertion and inference on many points, on which modern science clearly proves this system to have been as much in error as it was possible to be. It is strange to note how inadequate an idea Lucretius had of the vastness and complexity of the problem which he professed to solve. He has no real conception of the progressive advance of knowledge, and of the necessity of patiently building on humble foundations. The striking lines-- Namque alid ex alio clarescet nec tibi caeca Nox iter eripiet quin ultima naturai Pervideas: ita res accendent lumina rebus,[401] look rather like an unconscious prophecy of the future progress of science than an account of the process of enquiry exhibited in the book.