People are clever, but almost no one ever devises an optimal quip precisely at the needed moment. Therefore, virtually all great one-liners are later inventions - words that people wished they had spouted, but failed to manufacture at the truly opportune instant.

Forelimbs of people, porpoises, bats and horses provide the classic example of homology in most textbooks. They look different, and do different things, but are built of the same bones. No engineer, starting from scratch each time, would have built such disparate structures from the same parts.

No one-liner can ever be optimal.

If we are still here to witness the destruction of our planet some five billion years or more hence, then we will have achieved something so unprecedented in the history of life that we should be willing to sing our swansong with joy - Sic Transit Gloria Mundi.

No rational order of divine intelligence unites species. The natural ties are genealogical along contingent pathways of history.

The extreme rarity of transitional forms in the fossil record persists as a trade secret of Paleontology. Evolutionary trees that adorn our textbooks have data only at the tips and nodes of their branches; the rest is inference, however reasonable, not the evidence of fossils.

Our current drug crisis is a tragedy born of a phony system of classification. For reasons that are little more than accidents of history, we have divided a group of nonfood substances into two categories: items purchasable for supposed pleasure (such as alcohol), and illicit drugs.