Though it is
usual to preface the study of the Greek contributions to the sciences by a
consideration of what in the various disciplines had been achieved by
Egyptians, Sumerians,
Assyrians and the other peoples of the Near East, I shall not follow this habit. From the
beginning of history and long before it, all peoples, during their long
history, collected a
considerable amount of empirical knowledge, and even the oldest surviving texts often
mention different animals and give us an account of various medical practices which
require a precise knowledge of the pharmaceutical properties of different plants
and minerals, of anatomical and physiological data etc. However, all
this knowledge,
albeit codified and, occasionally, generalised to some extent, is always devoid of any
speculative content, as, vice versa, is usually the case with Greek culture. The Greeks
eventually derived such information from their neighbours (it was, indeed, an
established tradition that the first great Greek thinkers, such as Thales, Pythagoras,
etc., had learnt much of their knowledge during their true or supposed voyages in the
lands of the Barbarians). However the Greeks were able to reshape it in the guise of
theoretical generalisations, which can only be considered the forerunners
of
proto-philosophic and scientific thinking. At all events, there is very little
that can be considered as
‘biology’ in what we know of the thoughts of the Greek philosopherscientists preceding
Aristotle.
First of all, it
is clear that to all presocratic philosophers the distinction between the world of
living organisms and that of inorganic, non-living, matter was either obscure or has
definitely to be ruled out. The obvious
character which allows these philosophers to separate living from non-living
things was the fact that living things are ‘self-moving’ whereas non-living objects and
corpses have to be moved by something outside them. Now such a criterion was equivocal
(to Thales, among others, the lodestone was a living being as it was able to move
itself towards an iron object) and left an ambiguity of somewhat intermediate objects, such as
eggs or seeds. On the other hand, as they could not explain the apparently
spontaneous movements of inorganic bodies, such as earth, water, and
especially wind,
they naturally tended to attribute them to the whims of ‘personalities’, perhaps
different from those responsible for such ‘rational’ movements as those of the celestial
bodies. As a result we must deem that Thales’ statement “The world is full of Gods” is
a perfectly rational one.
We must here
stress an observation that has had a very lasting significance in the biology and
physics of the Greeks: death can easily be identified with the ceasing of breathing, and
winds may well look as the breath of the world, on the other hand there is no
motion apparently more spontaneous than wind, and its motion moves the seas, the clouds
and any other sufficiently light body. The Greek word ‘Pneuma’
(πνευ´μα) (and of ‘pneuma’ we shall have much to say) does not mean
breath as the act of breathing or the blowing wind, it means ‘the breath’,
independently from what is actually breathing. Thus the concept of ‘pneuma’ will slowly
evolve through the centuries, but it will always remain an important concept in all
biological and physical Greek theories. In order to
understand Greek science, philosophy and religion, two other concepts are significant:
namely that of ‘Noús’ (Nοοζ) and of ‘Nomos’ (Nóμοζ). Taken together they
characterise all that is rational both in men and in the cosmos: This, in the end, was the
basis of the progressive identification with Gods of many celestial bodies, who,
with their unchangeable and mathematically perfect movements, tell the
times of
terrestrial events. All the points
raised in the previous sentences, are already implicit in Homeric poems, which are
the oldest surviving documents of archaic Greek thought. Indeed in Homer
the word ‘soma’ (Σω´μα), body, is used only for corpses. Living beings are
always described by means of their ‘composing parts’, such as legs, arms, head etc. and of
their, so to say ‘active parts’: Thymos (Θυ´ μοζ), Nous and Psyché (Ψυχη´ ). Thymos
is that something which is responsible for emotions, while Nous is what is rational
and conscious. Lastly Psyché (literally ‘breath, puff ’, but also ‘butterfly’) is that which
makes an individual alive and, in men, their only immortal part. Thus we often
find sentences of the type “he was willing to do that, but his thymos paralysed his
legs”. On the other side, while ‘thymos’ is shared by men and animals, ‘Nous’ is common
to men and Gods. We shall see how these ideas were significant inlater discussion of the “vegetative soul, the appetitive soul and the rational soul”, which had a
great influence on the development of systematics, embryology etc. and that are still
implicit in many extant legislations. The fact that ‘Psyché’
and ‘Pneuma’ are to some extent synonyms led to a line of thought, which
began with a fragment of Anaximenes written around 546 BC and which literally
reads “Just as soul (psyché) is our air (pneuma) and keeps us together (but one may
also translate “controls us”) by that, so air and breath keep together (or “control”) the
whole world”. It then passed through stoic and neoplatonic philosophers, and had a
considerable impact on the development of the ideas of the relationship
between Macro-
and Microcosmos and went into vitalism down into the 20th century.Obviously the
Greeks could not overlook the significance of the relationship between the ‘soma’
(material body) of living beings and non-living bodies. So we shall shortly begin to
consider the evolution of concepts concerning the nature of what is ‘material’ in
the world, and more properly the increasing credit of the theory of the four ‘stoicheia’
(singular Στοιχει ´ ον), commonly translated as ‘elements’, but more
properly ‘material
principles’. According to the
essentials of the theory; all objects including the bodies of living beings, are
composed of matter, and in this we can identify a certain amount of dry
substance, that
is of ‘earth’, mixed with a certain amount of ‘water’. The breath or vital
pneuma (‘air’)
gives them life, and as they are moderately hot, they must contain also some ‘fire’. In fact the
theory of the four elements: earth, water, air and fire and of the four qualities,
opposed two to two, heat and cold, dampness and dryness, was expounded by Empedocles,
but has almost certainly much older roots. It was finally developed fully by
Aristotle (and, as we shall see, while it was accepted by many, it was
questioned even by
Aristotle’s friend Theophrastus). Furthermore, the theory had a great importance in
the whole development of sciences until modern times. All the
hypotheses advanced by ancient peoples in order to explain the origin and nature of things
are myths, and it is fascinating to follow how the ancient cosmogonies of purely
religious pattern (at least in the sense we currently give to these terms), such as those of
Hesiod, gradually change because of the unstated growing requirement of empirical
plausibility, and eventually become what we may term as scientific hypotheses or
theories. The Gods, not only for what concerns the first origin of things, but as
rulers of the present course of phenomena, change from somewhat whimsical
players with things and men into the rational guardians of a universal Nous. Greek
religious attitude was particularly apt for this change as, even since our
earliest testimonies, the
Impassive Deities: Ananke, the Moirae, Dyke, Themis, who all may be subsumed
under the Latin term of ‘Fatum’ (=that which must be and cannotbe otherwise), must be obeyed even by Zeus. There is no doubt that since the earliest times
the Greeks were quite convinced of an ambivalence in the relationship between
the individual man and the events which befell him: man may well make his
choices, but this only within the limits of what has been decreed by the
impassive Deities, first of these Ananke, and the Moirae, and by the ‘laws’:
Themis and Nomos. A choice different from the one so expected was indeed possible,
but it was the supreme offence (hybris) upon the Gods and the implacable
Nemesis was there to punish it. In this context the reply of Achilles to Thetis, who is
urging him to avoid his destiny leaving alone Hector and Troy, is typical: “Should I do it,
I would no more be Achilles!”. This attitude
almost naturally led to the belief in the existence of immutable laws in the universe,
a concept that is the very core of all scientific thinking as we conceive it. The
alternative is occasionalism, which was, indeed, advocated by quite a few Christian and by
many Islamic thinkers. They maintained that everything that happens is directly the
doing of God, who plays with men and things as puppets and that God’s laws are
not really laws, but simple sequels of events that might be changed at any time by God’s
will1. Starting from
the religious beliefs that we have summarised, Greek thought developed and, not
surprisingly, reached its greatest achievements in Mathematics and Astronomy,
fields where, because of the extreme regularity and comparative simplicity of phenomena,
the implementation of a rigorous conceptual framework could better succeed.
Chemistry and
Biology approached themselves to the ideal models of science only later and to a
limited extent because of the complexity of biological phenomena, and, in the case of
chemistry, because of the difficulty of quantitative controls in the absence of
sufficiently precise instrumentation. Aristotle is
quite clear in his distinction between science and empiricism; he maintains that science (or
philosophy) is the asking and answering the questions of how and why the
observed phenomena happen, while empiricism merely observes the phenomena and possibly
cares for the practical utilisation of the observations. We must here
remind the reader of a special difficulty in the understanding of the early Greek
philosophers. This is that, in order to explain their ideas, they usually use comparisons with
familiar phenomena, and it is not clear whether they thought of these
comparisons as real analogies or as rough approximations. So, for instance, by
the statement of Empedocles that sounds are moving air that hits inside our ear
onto a membrane hanging “like a rattle”, it is not clear whether he did in fact
know of the tympanum and had made a shrewd guess at its working, or whether his
was a fantastic idea such as the kind of connections that he believed to obtain
between the eye, fire and vision. The oldest Greek philosophers called
themselves ‘physiologists’, from the Greek words ‘physis’2, that is Nature and ‘logos’,
discourse, meaning that they were arguers
1 On this we
have a curious Quaestio quodlibetalis by
St. Thomas Aquinas: “Can God restore virginity to a girl who has lost it?”, The
answer being that though he may indeed restore the physical features of it,
even God can not cancel the fact that such loss had happened 2 ϕυ`σιζ is a
term that, in the oldest authors, like Hesiod, derives from the verb φυναι that
means to birth, to generate, thus it is used literally with the meaning of
‘birth of things’.about Nature.
And, indeed, their main problem is the origin and nature of things. It was only much
later - and when it had already reached a high complexity - that philosophy became
interested in other problems, such as that of the nature of the human mind, of the
principles underlying knowledge, and of morality. Anyway, the problem of Nature,
including biology, is always the foundation of Greek philosophy, even in those schools
that left it rather in the background.
REFERENCE
Alberto Mario
Simonetta, Short history of biology from
the origins to
the 20th century, ISBN 88-8453-108-X
© 2003, Firenze
University Press
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