 Moreover, there is perhaps in Hobbes’s method something like the middle step of regressus. For Hobbes, to know an effect through its causes is to know what the causes are and how they work: “We are said to know scientifically some effect when we know what its causes are, in what subject they are, in what subject they introduce the effect, and how they do it” (Hobbes 1655, 6.1). The requirement to know how the cause works, not just what it is, is analogous to the Zabarellan requirement to have distinct knowledge of a cause. Knowledge that the cause exists comes from the first step of regressus. Complete regressus, i.e., complete explanation, requires that you make a fuller investigation of the cause. For Hobbes, analogously, to get to scientia of the effect you need to understand, not just what the causes are, but how they work.