§ monic and epic arrows

This is trivial, I'm surprised it took me this long to internalize this fact. When we convert a poset (X,)(X, \leq) into a category, we stipulate that xy    xyx \rightarrow y \iff x \leq y. If we now consider the category SetSet of sets and functions between sets, and arrow AfBA \xrightarrow{f} B is a function from AA to BB. If ff is monic, then we know that A=Im(f)B|A| = |Im(f)| \leq |B|. That is, a monic arrow behaves a lot like a poset arrow! Similarly, an epic arrow behaves a lot like the arrow in the inverse poset. I wonder if quite a lot of category theoretic diagrams are clarified by thinking of monic and epic directly in terms of controlling sizes.