He [Aristotle] felt he was seeing Being from within. The Being of things may seen static. The changes and movements of bodies seem to end in stability. But in the reality "thinking," "Being" is not something static, not a quiet figure, but Being making itself, a continual self-creation; in sum, the word "Being" acquires the value of an active verb, of executivity, of making effective. This man, born on the rim of Hellas, substituted a dynamic concept for the static one of the pure Greeks. No longer will Being be exemplified by a geometrical figure that is pure aspect or spectacle; "Being" will henceforth be a thing's effort to sustain itself in existence. . . . The other examples Aristotle adduces in addition to thinking are seeing, being happy, loving, living. These too are movements with their "ending" in themselves. They all belong to the human realm and are "envisioned from within." . . . The notion of an energetic Being triumphs over the notion of static Being. (VI, 415, n. 1)
I am reminded of a saying 'to be is to be related'. I think this is Buddhist in essence. Buddhism rejects the idea of substance, of anything which is self-existent, that is, existing in its own right or independently of causes and conditions.
But what is a thing? A piece of the universe, there is nothing alone, there is nothing solitary nor walled off. Each thing is a piece of a larger one, it refers to the rest, it is what it is due to the limitations and confines that these place on it. Each thing is a relation among several. (I, 474-75)
There is an everyday reality formed by a system of loose, approximate, vague relations, which are sufficient for daily life. There is a scientific reality forged from a system of exact relations imposed by the necessity of exactitude. (I, 475)
And what is the being of a thing? An example will make it clear. The planetary system is a system of things, in this case of planets: before the planetary system was thought of there were no planets. It is a system of movements; that is, of relations. like determining a point in a quadrant. Without the other planets, the planet Earth is not possible, and viceversa; each element in the system needs all the rest: it is mutual relation among the others. According to this, the essence of each thing resolves itself in pure relations.
There is no deeper meaning in the evolution of human thought from the Renaissance to now : the dissolution of the category of substance into the category of relation. And since the relation is not a res, but rather an idea, modern philosophy is called idealism. and medieval philosophy, which begins with Aristotle, realism. (I, 480-81)
Each concrete thing is constituted by an infinity of relations. The sciences proceed discursively, they look for those relations one by one, and, therefore, they need an infinite time to fix them all. This is the original tragedy of science: to work for a result that it will never fully achieve.(I, 483)
Life is change of substance; therefore, co-living, coexisting, weaving itself into a network of relations, leaning one on the other, mutually nurturing one another, involving itself, potentiating itself. (I, 491)