From a commenter on Ta-Nehisi Coates’ blog in the ATLANTIC:
Aristotle, like Hobbes, did think that knowledge came from the senses, but he had a very different view of how senses worked. Aristotle believed that every physical object has a form or essence, and a substance. So a clay model of a tree and real tree share commonalities of form, although their substances are totally different. Aristotle also thought that the psyche is an instrument whereby we can receive the form of objects without the substance. He compares sensation to a signet ring making an impression of wax.Hobbes, however, does not really believe that the concept of “essence” is useful in explaining the world. He is basically a materialist. He believes that the only things worth talking about are matter and its interactions. Therefore, his account of how we obtain knowledge through the senses has to rely on interaction between matter.This might sound like an obscure difference, but it has a lot of consequences for how one studies the world. If you agree with Aristotle, the implication is that by observing the world, you can get an idea of the real essence of things. Acquiring theoretical knowledge is then a matter of thinking rationally about the implications of this knowledge. Thus physical science is a matter of everyday observation followed by rigorous thinking.However, if the information you get from the senses is just a bunch of particles bouncing off of your sensory organs, as Hobbes believes, then there’s good reason to be worried that the senses are unreliable, and you need to spend time carefully tweaking the information you get from the senses to make sure you have it right. This gives rise to an experimental model (which Hobbes’ contemporary, Francis Bacon, focused on far more than Hobbes did).As for how commonplace it was – Aristotelianism was basically the dominant philosophy from the time of Thomas Aquinas (1200s) up until the 1600s. Hobbes is writing around the time of transition away from Aristotle’s position as the preeminent thinker on matters such as this. I actually am not sure how dominant the view still was among academics by the time of the Leviathan.As an aside, the reason Hobbes talks about mediate and immediate interaction is that, at the time, people who subscribed to this materialst view did not believe that matter could interact with other matter at a distance. The only interactions allowed into the theory were direct ones. The view of no interaction at a distance was thrown out after Newton’s theory of gravity became the consensus view – since gravity is interaction at a distance.