He thought that the properties of living organisms were due to the mixture of these principles and elements in each part of the body, plus an animating force he called "pneuma", which got translated as "anima" in Latin, the word for "soul".
There were, in fact, a number of souls, ranging from growth, to motion, sensation, to thinking, and finally in humans, to reason.
It was not a complete theory of evolution by any means, although Haeckel and Osborn claimed he was a "prophet" of Kant, Laplace, Lamarck and Darwin.
It was only his persistence and sound experimental and analytical procedures that finally compelled most biological and medical scientists to give up their ideas of the naturalistic origin of life and their treatment of disease as based on this notion.In books also other animalcules are found, some resembling the grubs found in garments, and some resembling tailless scorpions, but very small.As a general rule we may state that such animalcules are found in practically anything, both in dry things that are becoming moist and in moist things that are drying, provided they contain the conditions of life." "Some writers actually aver that mullet all grow spontaneously.He thought there were four elements and a fifth essence later called the "quintessence" or "ether" that occurred only beyond the moon, in the heavens.The four terrestrial elements are, of course, earth, air, fire and water, each of which is a principle of hot, cold, dry and wet .In the "So with animals, some spring from parent animals according to their kind, whilst others grow spontaneously and not from kindred stock; and of these instances of spontaneous generation some come from putrefying earth or vegetable matter, as is the case with a number of insects, while others are spontaneously generated in the inside of animals out of the secretions of their several organs." "As a general rule, then, all testaceans grow by spontaneous generation in mud, differing from one another according to the differences of the material; oysters growing in slime, and cockles and the other testaceans above mentioned on sandy bottoms; and in the hollows of the rocks the ascidian and the barnacle, and common sorts, such as the limpet and the nerites." "Other insects are not derived from living parentage, but are generated spontaneously: some out of dew falling on leaves, ordinarily in spring-time, but not seldom in winter when there has been a stretch of fair weather and southerly winds; others grow in decaying mud or dung; others in timber, green or dry; some in the hair of animals; some in the flesh of animals; some in excrements: and some from excrement after it has been voided, and some from excrement yet within the living animal, like the helminthes or intestinal worms." "Other animalcules besides these are generated, as we have already remarked, some in wool or in articles made of wool, as the ses or clothes-moth.And these animalcules come in greater numbers if the woollen substances are dusty; and they come in especially large numbers if a spider be shut up in the cloth or wool, for the creature drinks up any moisture that may be there, and dries up the woollen substance. A creature is also found in wax long laid by, just as in wood, and it is the smallest of animalcules and is white in colour, and is designated the acari or mite.From the facts above enumerated it is quite proved that certain fishes come spontaneously into existence, not being derived from eggs or from copulation.Such fish as are neither oviparous nor viviparous arise all from one of two sources, from mud, or from sand and from decayed matter that rises thence as a scum; for instance, the so-called froth of the small fry comes out of sandy ground.Then we will look at the modern - post-Pasteur and post-Darwin - developments in Origins of Life research.The first western thinker to suggest that life arose spontaneously was probably , a Milesian philosopher (in what is now Turkey) who wrote in the 6th and 5th centuries before Christ (611-547 BCE).