 Moreover, Hobbes thinks that understanding is a sort of imagination. That is, the faculty of imagining is responsible for understanding, as well as for compounding images and for memory. Understanding is, Hobbes says, “[t]he imagination that is raised in man (or any other creature endued with the faculty of imagining) by words or other voluntary signs” (Hobbes 1651, 2.10). Understanding is not restricted to humans. So, for example, “a dog by custom will understand the call … of its master” (Hobbes 1651, 2.10). But humans have a sort of understanding that other creatures lack. A dog, for instance, can understand the will of its owner, say that its owner wants it to sit down. In general, the understanding that non-human animals can have is the understanding of will. But humans can also understand the “conceptions and thoughts” (Hobbes 1651, 2.10) of others from their uses of language.