In Aristotle's view, there are precisely five kinds of "predicables": things we can predicate of, or attribute to, a subject. Three are "essential" (genus, species, difference); two are inessential (property and accident). We use this in scientific classification of species, for example - like the red fox (vulpes vulpes). Here Aristotle further unfolds his view of the world, where we encounter things that exist and have certain features independent of our perception of them. Also here we explore Aristotle's account of the "four causes" by which any thing is brought about.