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.

Death is the ultimate enemy - and I find nothing reproachable in those who rage mightily against the dying of the light.

The telephone is the greatest single enemy of scholarship; for what our intellectual forebears used to inscribe in ink now goes once over a wire into permanent oblivion.

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.

Current utility and historical origin are different subjects.

Theory and fact are equally strong and utterly interdependent; one has no meaning without the other. We need theory to organize and interpret facts, even to know what we can or might observe. And we need facts to validate theories and give them substance.

You put three facts together - that all organisms produce more offspring that can survive, that there's variation among organisms, and that at least some of that variation is inherited - and the syllogistic inference is natural selection.