How many angels can dance on the head of a pin? dancing on a needle's point occurs in an expository work by the English divine, William Sclater (1575-1626). In "An exposition with notes vpon the first Epistle to the Thessalonians" (1619), Sclater claimed that scholastic philosophers occupied themselves with such pointless questions as whether angels "did occupie a place; and so, whether many might be in one place at one time; and how many might sit on a Needles point; and six hundred such like needlesse points." Harrison proposes that the reason an English writer first introduced the "needle’s point" into a critique of medieval angelology is that it makes for
Flying and gliding animals can glide at a shallower angle than parachuting animals, allowing it to cover greater horizontal distance in the same loss of altitude, and reach trees further away. Unlike most air vehicles, in which the objects that generate lift (wings) and thrust (engine/propeller) are separate and the wings remained fixed, flying animals use their wings to generate both lift and thrust by moving them relative to the body. This has made the flight of organisms considerably harder to understand than that of vehicles, as it involves varying speeds, angles, orientations, areas, and flow patterns over the wings. A bird or bat