Chapter 26
Species and property have this in common: that they are mutually predicable of each other, that is to say, that they are convertible; and that they are participated in equally because they do not communicate themselves to any one of the individuals participating in them more or less than to any other. Differences between species and property are: that the species is essential, whereas the property is super-added to the essence; that the species is always in act, whereas the property is always in potency and not always in act; and that those things which have different definitions are manifestly themselves different also.
See alternate