Surveys mathematical and epistemological understanding of risk in the Western era, focusing on it’s roles in modern investing. Initially the problem concerned Renaissance-era advances in quantitative certainty, while gradually the understanding that past results cannot determine (but only suggest) future events introduced a moral / emotional context. Two poles in the latter 20th-century understanding are diversification (reduced likelihood of losing it all at once) and chaos theory (nonlinerarity tells us that ends are not proportionate to events). Whichever may become predominant according to events, risk has become a scientific approach to increasing opportunity for sustained gains (or, reduced exposure to unwanted outcomes). Well synthesized if occasionally blocky prose. Worth re-reading; next step, the au courant Black Swans.