SANGAMON'S PRINCIPLE

'Sangamon's Principle' is a principle put forward in Neal Stephenson's novel Zodiac by the character Sangamon Taylor, an environmental activist, which states that simple molecules make better recreational drugs than complex ones, because you never know what side effects more complicated compounds will have.
Stephenson's other characters may not observe the same principles. In particular, the Baroque Cycle's Robert Hooke uses cannabis.
The following is a rough list of drugs, ordered according to Sangamon's Principle:

# of Atoms	Drug	Formula
2	Oxygen	O2
3	Nitrous oxide	N2O
9	Ethanol (alcohol)	C2H6O
24	Caffeine	C8H10N4O2
26	Nicotine	C10H14N2
29	Methylenedioxymethamphetamine (ecstasy)	C11H15NO2
36	Psilocybin (mushrooms)	C12H17N2O4P
43	Cocaine	C17H21NO4
49	Lysergic acid diethylamide (LSD)	C20H25N3O
50	Diacetylmorphine (heroin)	C21H23NO5
53	Tetrahydrocannabinol (cannabis)	C21H30O2

Sangamon's Principle is often quoted by nitrous oxide (N₂O) users to justify its use over other drugs.