A famous Russian biologist (author of Vitality) discusses the physical and spiritual sources of happiness -- the basal metabolism, the chemistry, the influence of disease, temperament, rhythms in controlling happiness. Should be of interest to the customer who liked Glands Regulating Personality (Berman) and Recreating the Individual (Hinkle) -- cases drawn from history and from public life, from legend and anecdote; human interest element strong; note of hope in that happiness is within control. Plea to make intellect a leader, not a dictator, to cultivate ""not thinking"", to give freedom to emotions. The style is more popular than in his Vitality -- the subject of more general interest. With sales record of Vitality, this should do well.