Proverbs 30:18-19

These four "ways" (Heb. derek) have several things in common that make each of them remarkable. All are mysterious (inexplicable), non-traceable, effective in their element, and aggressive. "The way of a man with a maid" refers to the process by which a woman comes to love a man. The point of these four snapshots seems to be, that in view of remarkable phenomena such as these, arrogance is absurd and humility only reasonable (cf. Job 38-41).