Ever since Descartes suggested that matter is defined by extension, philosophers had been proposing theories as to what Cartesian idea of matter had overlooked, since clearly, extension as such is not yet matter. Darjes enters this discussion in the section on somatology, or theory of bodies or composite entities. He notes that to make a set of multiple entities into a unified entity, it isn't enough just to put them together. Instead, these parts must also cohere with one another.
Now, as we saw in the previous post, Darjes thought that in order that entities can cohere, all of those entities must be non-spontaneous, but also some of them must be active. In other words, there are no completely passive bodies in Darjesian metaphysics, only more or less active. The level of activity in bodies can even be perceived, Darjes suggests, since the difference of fluids and solids reduces to it – fluid bodies have more active entities in them than solid bodies, which have only so much active entities as required for the sake of coherence. Since the difference between fluids and solids is ultimately based on the essential difference between active and passive entities, the difference between fluids and solids must also be essential, Darjes concludes. Somewhat surprisingly, this means that fluids cannot really change into solids or vice versa.
A significant part of philosophical treatises of corporeal objects from this period often include an account of simple mechanical interactions, in which two bodies collide with one another. Darjes is no exception to this rule. He considers several cases – what if only one is moving or both, what if colliding bodies are solids or fluids etc. We need not get too far into the details, but just to note the general attempt to determine the result of the collision from the constituents and the structure of the colliding bodies. For instance, in a collision between a solid and a fluid, the fluid gives away, because a fluid body has more active constituents, which will move according to their own drive, as soon as bonds of coherence holding them together loosen a little bit, while the solid can remain unified in an easier manner.
As a final part of the first tome of his metaphysics Darjes introduces a discipline called mechanology, a study of machines. Machines, for Darjes, are systems of non-spontaneous entities, in which systems, again, mean collections of entities that can affect one another. Systems and therefore also machines are to be clearly differentiated from cohering bodies – in a system, the constituting bodies do not form a single entity, but remain independent of one another. Darjesian understanding of machines is quite extensive – the constituting parts of machines can be solid or fluid bodies or theoretically even elements. Indeed, the whole mechanology remains on a quite general level, where Darjes finds out such revelatory truths as that the state of a machine depends on its previous state.
The second tome of Darjes metaphysics moves then to the investigation of soul, which shall also be the topic of my next post.