The last of materialistic and monistic philosophers of ancient Ionia, Diogenes of Apollonia, around the years 440-430 BC, also went right down the same path as his predecessors and held, openly and explicitly, that the air is the 'beginning' of all things.
Just some fragments of the writings of this philosopher, belonging to his work 'On the Nature', are preserved, which were collected by Simplicius. But if we listen to different quotations, he seems to have written several more books, one 'Against the Sophists', one 'On meteorology', and one on medicine that he would have entitled 'On the Nature of Man', which Galen would referred when he said that Diogenes had compiled diseases and their causes and remedies in a treaty. Everything indicates that Diogenes of Apollonia was a doctor by profession and would have published, indeed, this medical treatise in which their notions about the origin of diseases would appear related, surely, with the ideas of his general theory, which ones have been preserved and we'll see here.
Diogenes thought the world and its parts were ordered in the best way possible by the intervention of a divine intelligence that would be present in originating substance that is air. By the provisions of this 'air intelligence' the world is not a chaos but a real cosmos, where everything is distributed according to some regularities, like the seasons, day-night cycles, weather variations...
The essential substance the whole of reality is air, said Diogenes, for the obvious reason that living beings if they can live is by breathing air. The air is 'soul' understood as vital principle (which gives life), as deduced from the fact that life leaves the body when breath leaves.
This idea was already in some uses of 'zimós' and 'psijé' of Homer, who Diogenes praised (claimed Filodemo) because "he told on the divine not poetic but truthfully and claimed that Zeus himself is the air explicitly".
Diogenes relates both outdoors air and the air contained in the body, in the vein of Anaximenes, and relates the term 'pneuma', which means soul or spirit, as a synonym for breath and wind. Air is the giver of life, thus becomes God, because if it gives life it has absolute power on everything, on all the phenomena of human existence. It is infinite, eternal and immortal, it is not subject to time limits of life of any body, it does not perish with it (on the contrary, is it that gives and removes life) and it extends everywhere.
The air is responsible for the regularities and irregularities of the cosmos, and also of the human psyche. Not that the air contains intelligence, but it is intelligence because it is what orders and disposes the mind and the entire cosmos, it really is the intellectual soul, is what has knowledge. "The air is great and powerful, eternal and immortal and knowing many things" (Simplicius, Physics 153, 20).
One of the reasons that prompted Diogenes conceive the air as the principle of all things and as 'god' was, as mentioned in the case of Anaximenes, the fact that the air is so subtle substance that eludes the senses and seems intangible or incorporeal. Another reason, also commented, is its omnipresence: "the air rises to the top and down to the lowest and fills all the spaces." Incorporeality and omnipresence are two attributes of the apparent 'metaphysical' or 'divinity' of air, but actually, paradoxically, they are just a pure physical phenomenon of nature.
One difference with Anaximenes lies in the fact that, to Diogenes, changes that would explain the phenomena of nature are not confined to the rarefaction or condensation of air, but also another factor involved is its temperature. To Diogenes, the distinctive feature of divinity and humanity is heat, in complicity with the ideas of Heraclitus on the 'igneous ether'. To Diogenes of Apollonia intelligence is hot air, warmer than the atmosphere although not quite as the ether that surrounds the sun.
The temperature of air producer of intelligence, what Diogenes says is very interesting, would register continuous slight temporary modifications which may explain, in turn, the numerous and unpredictable variations that occur in time in our perception, our thinking and our psyche in general.
A moderate heat would be the distinctive feature of air-soul or 'pneuma', which would explain, according to this wise, fluctuating changes in mental states and acts, from the most subtle variations of thought and perception to the most extreme states of sleep and death, which also correspond to extreme changes of 'pneuma': "Diogenes says that if the blood, spread throughout the body, fills the veins and pushes containing air toward chest and bottom belly, sleep occurs and the central part of the body is heated, but if all the air goes out of the veins, death occurs" (Aetius, V 24, 3).
Clearly Diogenes of Apollonia thought as a physician and led theses of Anaxímenes to the field of physiology. He did not maintain outside the body but he entered to explaining how the air acts in the body to produce the phenomena of soul. The universal air gets into the body by breathing and flows, driven by the blood of the veins of the body, to the brain, which acts as an interpreter of fluctuations or 'logos' of this universal air.
The air inside our body partakes of the 'divinity', is part of it, by transmiting the universal to our personal soul. Our thinking becomes a kind of organ sensitive to fluctuations ('logos') of air. The ethereal element extends throughout the universe and also acts on the bodily 'pneuma' of each person by the action of breathing and blood circulation. Accordingly, changes in our mental and cerebral activity are due to variations in atmospheric air (in terms of temperature, density...) from the outside world but the body 'interpreted' by its natural functioning creating one cerebral and mental 'logos', internal and subjective.
The seat of soul is the brain. The brain is the organ that interprets changes in air, it is which intellects. The brain is the instrument that uses air to think. The (other) sensory organs are subordinated to this main organ that produces the act of understanding. The brain 'resonates' with certain variations of air that give it a 'logos', as ear resonates under certain frequencies to offer sounds and sonorous languages. Outside air 'feeds' the soul and comes first to the brain and stays there; the remainder spreads throughout the body through blood vessels and engages, thus, the whole body in insights and emotions. Whole body, but especially the brain, 'vibrates' with air.
Diogenes maintains that, when a large amount of air is mixed with the blood and lightens it according to its less heavy nature, and penetrates, subtilized, whole body, pleasure originates; and when air is present against its lightweight nature, by action of moisture, and does not mix to be weighed, blood clots, weakens, it becomes denser and hence arises displeasure and pain. Similarly moods, such as trust and its opponents distrust and shame, and health and its contrary illness, originate, says Diogenes.
What is the thought itself is caused by the pure, dry and hot air, as all wet emanation inhibits intelligence. This is the reason, he argues, because the thought appears diminished in sleep, in drunkenness and satiety, because in them the air is concentrated in the belly and it become dirty by elements that are there, he says.
Another proof that moisture removes intelligence is indicated from that other living beings are inferior in intelligence to man because they breathe the air closest to earth, which is wetter and impure, he says. (The birds breathe fresh air, true, but he argues that they have a similar to fish constitution, because its flesh is solid and air does not penetrate completely but is detained around the the abdomen... and understands that plants are totally deprived of intelligence for the simple fact that have no air in.)
To Diogenes intelligence is the same as the vital intensity. This is very interesting. There are different degrees of intelligence and different degrees of vital intensity corresponding to the first. These quantitative differences in intelligence and vitality would be originated from, according to him, besides the properties of the surrounding air, the permeation of air into the body. The least, plants, then fish and birds, have a low degree of vitality and intelligence, it is assumed, by low penetration and diffusion of air inside.
The human being is the one with a higher degree of intelligence and vitality, because he absorbs and disseminates a lot of air into his body, it is understood; but he is also highly variable from one moment to another, there is nothing static in him, quite the contrary. There are times when people live life intensely, when everything flows so fast and absorbent, which are those moments that we have a deeper and more vivid thinking. At other times the opposite happens, we are unable to mentally prepare anything and understanding of things is absent, and our existence is drab and boring. In these times, unlike the first, the degree of our vital intensity is low, such as our intelligence. And this changes would obey to changes in qualities of air and / or in our way of breathing. Intelligence (thought) is so unstable and volatile as the element that generates it...
The thought or intelligence, for the philosopher of Apollonia, is nothing 'superior' emerging from elementary 'lower' activities but is at the same level as sleep, senses, pleasure and pain, feelings, health... All are 'sensations' produced by the air. Everything is at the same level. The outside air comes into contact and mixes (or simply waves) with the air inside the sensory organs and the brain, through the veins or blood vessels.
To Diogenes insights come from air, which takes over the whole body through veins and blood, especially in those propositions in which the veins itselves provide an "adequate anatomy" (Simplicius, Physics 153, 13). The thought, the intellectual soul, is generated by the correspondence between the air and the arrangement of our veins and our brain. The clarity of perception and intellect of a particular proposition depends on the subtlety of air that diffuses into our body, and on the finesse and the straightness of the channels through which spreads: on the resultant of the specific anatomy of involved veins.
When air is mixed with the blood and is permeated in the brain and the whole body, the feeling of pleasure and vivid thought arises. Thought depends on the purity and dryness of air and, as pleasure, arises when air is mixed with blood, subtilizes it, and spreads throughout the body through the vascular network. Thought and pleasure are very similar things in reality. Think the world in an understandable way, understand it (intellective knowing), is a powerful form of pleasure. So, intelligence, thinking, vital intensity and pleasure are totally united in Diogenes. Vitality, enjoyment, insight, understanding, thought, reason... are interrelated in its own essence if they are not the same thing. Many philosophers have intuited that the understanding of the world is the greatest pleasure to which man can aspire, but have failed to explain the reason. Diogenes of Apollonia, the physical, the forgotten, did.
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