From the Beginning to Plato

EMPEDOCLES 175
But the carapace is also the sea-turtle’s bone structure. In this and in many
other fragments Empedocles shows a remarkable first awareness of biological
analogy and homology in similarities found between plant and animal structures.
The elements themselves are first called rizōmata, or root clumps, and this type
of language is extended throughout the natural world in a variety of contexts.
Empedocles regarded humans as plants that grow from ‘shoots’, he called the
auricle of the ear a ‘sprig of flesh’, he had a common word for the bark of a tree
and for the skin of a grape and apple peel, olive trees were said to bear ‘eggs’,
and amnion was the term used both for the skin of an egg and the caul of an
embryo. Processes similarly correlate, and it seems to be a similar change in the
liquid, a sēpsis, which makes wine of water, yoghurt of milk and colostrum of
blood. Connections between primitive and more advanced species were drawn
when horses’ manes were seen as analogous to the spines of hedgehogs, and a
famous fragment took this further:
Hair, leaves, the close-packed feathers of birds and scales on strong limbs
—as the same they grow.
(fr. 82)
The shared function here of covering and protection crosses the forms of life and
the different elements to link humans and plants in land, birds in the air, and fish
in water.
PERCEPTION AND COGNITION
Another advance in the history of science came when Empedocles originated the
concept of pores and effluences to explain the workings of the organs of senses
in animals and humans, a theory which also extended the range of homology
through the various species. The medical philosopher Alcmaeon had previously
suggested that channel-like pores led from the eye to the brain, but Empedocles
set up a universal theory of perception, according to which all bodies have pores
close packed on their surfaces, and effluences like films ‘from everything in
existence’ are capable of entering the opening of these pores where there is
symmetry between them. According to his method Empedocles gave some
common examples of the theory at work before arguing for its extension over a
wider range. He cited the way in which water can mix with wine but not oil as
evidence for symmetry and asymmetry of the pores and ‘thick parts’ of the
liquids. Another example was when saffron dye became firmly fixed into a piece
of linen, and the magnet could be explained by effluences dragging the iron until
it closes with the pores in the stone. Something like this also happens in nutrition
and growth, where nourishment is broken up in the organism and distributed to
appropriate parts of the body according to their fit, for like substances are
attracted to their like, and unite with them: