"Power, Patronage, and the Authorship of Ars" is a study of books on the mechanical arts that appeared in the fifteenth century from Italy and south Germany. At this time a significant proliferation of such books occurred, some profusely illustrated, others exclusively textual. They include Latin books on military apparatus and other kinds of machines, German-language codices on gunpowder artillery and machines, humanist treatises on painting, sculpture, architecture, and the military arts, and vernacular writings on such subjects by practitioners. The author argues that the patronage that encouraged the creation of such books developed because of a new close alliance between political and military praxis and the mechanical arts. She suggests that such authorship elevated the status of the mechanical arts by explicating them in writing, rationalizing them, and associating them with ancient traditions. They were thus prepared for appropriation by the new experimental philosophy of the next era.

Descartes's Dioptrics is more than a mere technical treatise on optics; it is an essay in the "practical philosophy" that he claimed could render us "masters and possessors of nature." Descartes's practical intent is indicated first by the instrumentalist character of his derivation of the sine law of refraction, which is based on a heuristic and readily mathematizable model that requires no consideration of light's "true nature." Descartes's subsequent discussion of human vision is an extended critique of nature's workmanship that grounds the possibility of improving vision by artificial means. I suggest that this critique is the source of Descartes's doctrine that the purpose of sensory perception is to preserve the mind-body composite, not to provide knowledge of the essential nature of things. Accordingly, the ultimate goal of the Dioptrics is to "master" human vision by raising it from a mere means of self-preservation to an instrument of scientific knowledge.

Raymond Pearl, head of biology at the Maine Agricultural Experiment Station from 1907 to 1916, conducted extensive research on increasing egg production in the domestic chicken. He wanted his work to satisfy the demands of academic scientists as well as the practical and economic demands of farmers. His case highlights the close relationship that existed in the early part of this century between practical farming concerns and scientific studies of inheritance. Agricultural scientists needed to take account of actual farmer activities, since farm breeding work predated the efforts scientists were undertaking to understand heredity. Pearl considered the work of practical farmers and breeders in his own scientific research and thought about how his work, in return, would contribute to practice.

In 1962 Sidney Cohen presented the medical community with its first warning about the dangers of the drug LSD. LSD had arrived in the United States in 1949 and was originally perceived as a psychotomimetic capable of producing a model psychosis. But in the mid 1950s intellectuals in Southern California redefined LSD as a psychedelic capable of producing mystical enlightenment. Though LSD was an investigational drug, authorized only for experimental use, by the late 1950s psychiatrists and psychologists were administering it to cure neuroses and alcoholism and to enhance creativity. Cohen's 1960 study of LSD effects concluded that the drug was safe if given in a supervised medical setting, but by 1962 his concern about popularization, nonmedical use, black market LSD, and patients harmed by the drug led him to warn that the spread of LSD was dangerous. The subsequent government crackdown and regulation of LSD preceded the 1960s drug movement and was prompted by medical, not social, concerns.