The leech has two daughters: "Give" and "Give". Three things will never be satisfied; four will never say "Enough" - The afterlife, the barren womb, earth that still demands water, and fire they never say, "Enough".

Proverbs 30:18-31

Three things cause wonder for me; four are beyond my understanding: The way an eagle flies in the sky, the way of a serpent on a rock, the way of a ship on the high seas, and the way of a man with a young woman. This is what an immoral woman is like: she eats, wipes her mouth, then says "I've done nothing wrong." read more.
Under three things the earth trembles, under four it cannot remain steady: Under a slave when he becomes a king, a fool when he is overfed, an unloved woman when she finds a husband, and a servant girl who inherits from her mistress. Four things on earth are small, but they are very, very wise: Ants aren't a strong species, yet they prepare their food in the summer. The rock badgers aren't a strong species either, yet they build their dens in the rocks. Locusts have no king, but they all swarm in ranks. Spiders can be caught by the hand, yet they're found in kings' palaces. Three things are stately in procession, four which are stately in their gait: The lion, mighty among the beasts, retreats before nothing. The strutting rooster, as well as the goat, and a king with his army.