The philosophers of antiquity, interrogated as to the cause of these phenomena, were provided with a ready and a plausible answer. It did not enter their minds even to doubt that these low forms of life were generated in the matters in which they made their appearance. Lucretius, who had drunk deeper of the scientific spirit than any poet of ancient or modern times except Goethe, intends to speak as a philosopher, rather than as a poet, when he writes that "with good reason the earth has gotten the name of mother, since all things are produced out of the earth. And many living creatures, even now, spring out of the earth, taking form by the rains and the heat of the sun."[1] The axiom of ancient science, "that the corruption of one thing is the birth of another," had its popular embodiment in the notion that a seed dies before the young plant springs from it; a belief so widespread and so fixed, that Saint Paul appeals to it in one of the most splendid outbursts of his fervid eloquence:—
"Thou fool, that which thou sowest is not quickened, except it die."[2]
[Footnote 1: It is thus that Mr. Munro renders
"Linquitur, ut merito maternum nomen adepta
Terra sit, e terra quoniam sunt cuncta creata.
Multaque nunc etiam exsistant animalia terris
Imbribus et calido solis concreta vapore."
De Rerum Natura, lib. v. 793-796.
But would not the meaning of the last line be better rendered "Developed in rain-water and in the warm vapours raised by the sun"?]
[Footnote 2: 1 Corinthians xv. 36.]
The proposition that life may, and does, proceed from that which has no life, then, was held alike by the philosophers, the poets, and the people, of the most enlightened nations, eighteen hundred years ago; and it remained the accepted doctrine of learned and unlearned Europe, through the Middle Ages, down even to the seventeenth century.
It is commonly counted among the many merits of our great countryman, Harvey, that he was the first to declare the opposition of fact to venerable authority in this, as in other matters; but I can discover no justification for this widespread notion. After careful search through the "Exercitationes de Generatione," the most that appears clear to me is, that Harvey believed all animals and plants to spring from what he terms a "primordium vegetale," a phrase which may nowadays be rendered "a vegetative germ"; and this, he says, is "oviforme," or "egg-like"; not, he is careful to add, that it necessarily has the shape of an egg, but because it has the constitution and nature of one. That this "primordium oviforme" must needs, in all cases, proceed from a living parent is nowhere expressly maintained by Harvey, though such an opinion may be thought to be implied in one or two passages; while, on the other hand, he does, more than once, use language which is consistent only with a full belief in spontaneous or equivocal generation.[3] In fact, the main concern of Harvey's wonderful little treatise is not with generation, in the physiological sense, at all, but with development; and his great object is the establishment of the doctrine of epigenesis.
[Footnote 3: See the following passage in Exercitatio I.:—"Item sponte nascentia dicuntur; non quod ex putredine oriunda sint, sed quod casu, naturae sponte, et aequivocâ (ut aiunt) generatione, a parentibus sui dissimilibus proveniant." Again, in De Uteri Membranis:—"In cunctorum viventium generatione (sicut diximus) hoc solenne est, ut ortum ducunt a primordio aliquo, quod tum materiam tum elficiendi potestatem in se habet: sitque, adeo id, ex quo et a quo quicquid nascitur, ortum suum ducat. Tale primordium in animalibus (sive ab aliis generantibus proveniant, sive sponte, aut ex putredine nascentur) est humor in tunicâ, aliquâaut putami ne conclusus." Compare also what Redi has to say respecting Harvey's opinions, Esperienze, p. 11.]