Collection of seventeen nonfiction science essays. It was the ninth of a series of books collecting essays from The Magazine of Fantasy and Science Fiction.

The Problem of Left and Right
1 — Odds and Evens
2 — The Left Hand of the Electron
3 — Seeing Double
4 — The 3-D Molecule
5 — The Asymmetry of Life

The Problem of Oceans
6 — The Thalassogens
7 — Hot Water
8 — Cold Water

The Problem of Numbers and Lines
9 — Prime Quality
10 — Euclid's Fifth
11 — The Plane Truth

The Problem of the Platypus
12 — Holes in the Head

The Problem of History
13 — The Eureka Phenomenon
14 — Pompey and Circumstance
15 — Bill and I

The Problem of Population
16 — Stop!
17 — ...But How?