Sharp-tongued and incisive as ever, Medawar explores the very pith of science in a series of short chapters--deliberately brief, because he himself found maximum insights in similar exercises in brevity (Shelley's Defense of Poetry, Descartes' Discours), and not from such as the writings of Alfred North Whitehead. Medawar's aim is to clarify for lay readers what science is, who practices it, and what limits there are to the pursuit. Much of the first concern echoes the format of Aristotle to Zoos: brief paragraphs that discourse on science and unintelligibility, science and culture, science and the ""Mandarins' Fingernails"" (laying to rest the notion that exalts ""pure"" over ""applied"" science). In general, Medawar presents science as an imaginative pursuit dependent on prepared minds who choose the field because they're curious and can make those ""happy guesses"" that lead to experimental testing. Out the window go notions of logical procedure or foolproof methodology--hence out the window go ideas that scientific discoveries can be dictated in advance. There are some wonderful examples of happy guesses and unexpected findings (particularly from Medawar's own field of immunology). As for the limits, there's a twofold answer: no limits if the questions are the sort science can address--researchable questions to be tested against reality; but yes, limits if the questions concern the nature, origin, and destiny of man, or problems of evil and such, for which myth, religion, or ""imaginative literature"" are appropriate resources. For scientists, there are no surprises in what's said--but there's pleasure for everyone in the way it's said.