Stoic philosophy had a remarkable infusion many centuries after its development. In the 16th and 17th centuries there is a strong revival in Europe of stoic doctrines that will influence Descartes, Kant and Hegel.
The Stoics reduced the four Aristotelian causes to two only principles:
A Passive Principle: Matter
An active principle: the universal logos.
The Logos is not immaterial but of a corporeal nature. Only what acts or suffers an action is real, and since only one body can act or suffer, everything real is corporeal. Stoic doctrine is strictly materialistic. Matter lacks qualities and is passive, being equivalent to Aristotelian raw material.
The active substance is simultaneously an efficient cause and also, in a sense, a formal cause of what happens since it contains the “seeds” from which all things develop. Only the Aristotelian final cause is missing.
The active substance (universal reason, active fire and artist that governs and produces everything and everything penetrates, is called “God”. The universe is therefore an animated and divine All, which corresponds to a pantheistic vision of the universe. Nothing escapes the immanent law governing the Whole because events are determined by an inexorable causal chain. This “necessity” that governs the cosmos, is called destiny or providence but does not correlated with the Blind Hado of Greek Mythology, is a necessary, but absolutely rational order.
The world, which is a lively and harmonious being, has a life of its own:
The “great year”, which is a cycle, part of the original fire, develops by the appearance (from fire) of air, water, earth and all the bodies that are composed of these four elements, finally returning to fire.
A universal conflagellation ends the cycle of the world, which restarts again, and since all the dimensions of each cycle are neceary, each cycle repeats exactly the previous cycle.
Nor do there exist but concrete “individuals”, who are always different from each other, says Cicero:
“Every thing has its own character and nothing is identical to anything else” -
Each individual is characterized by an inner tension, a way of being or squeezing that cannot be repeated in another. The universal (just as the Ideas in Plato or the form in Aristotle) lacks reality. But although there are only individuals, they are linked together and the whole world is a gigantic harmony of correlations and interdependencies. And one law governs all this diversity, emerging the concept of “natural law” and “providence”.
For the Stoics, it makes no sense to speak of evil in the world, because nothing that happens can be evil in itself, for judging it so is a consequence of our limited vision of worldly events.
Man is a part of the harmonious universe and equally emphasizes individuality as well as the need to submit to a universal order.
The human soul is corporeal (“an enlivening and genousal murmur that comes from the parents, exits throughout the body and is mortal”). It contrasts this approach with that of Plato and even Aristotle since divisions are not contemplated but rather supports the unity of the parties, with a rational and hegemonic principle of which radiates a kind of “tension” towards all parts of the body and extends to the five senses, the reproductive part and the word.
There is no agreement regarding the physical location of this conception of the soul (hegemonikon), some are inclined to place it in the head and others in the heart. In any case, just as fire would be the beginning of the world, the soul would be the one that gives birth to the body by modeling and developing it from the embryonic state.
“Reason has been given to men as the most perfect function, so that for them to live according to reason is to live according to nature, since it is a guide of trends. For this reason Zeno said - and he was the first to say it - in his book on 'Human Nature', that the supreme purpose of man is to live conformity with nature, which is the same as living by virtue, to which nature leads us to virtue.” -Diogenes Laercio
The moral good of man consists in living in accordance with total nature and with pria nature, which is nothing but part of it. This is the same as living according to reason. It therefore refers to the Universal Reas on that governs the order of Nature, which means living in harmony with the Whole or rather, performing the duty which is nothing other than what reason commands to do. This thought will evolve towards Kantian ethics where the relationship between ethics and reason will reach its maximum expression.
In line, virtue is the permanent willingness to live in harmony with reason and duty. The Stoics argue that virtue is one and does not admit degrees: one is or is not virtuous because one who has one virtue has all of them.