Sometimes in the course of our adventure we came upon worlds inhabited by intelligent beings, whose developed personality was an expression not of the single individual organism but of a group of organisms. In most cases this state of affairs had arisen through the necessity of combining intelligence with lightness of the individual body. A large planet, rather close to its sun, or swayed by a very large satellite, would be swept by great ocean tides. Vast areas of its surface would be periodically submerged and exposed. In such a world flight was very desirable, but owing to the strength of gravitation only a small creature, a relatively small mass of molecules, could fly. A brain large enough for complex "human" activity could not have been lifted. In such worlds the organic basis of intelligence was often a swarm of avian creatures no bigger than sparrows. A host of individual bodies were possessed together by a single individual mind of human rank. The body of this mind was multiple, but the mind itself was almost as firmly knit as the mind of a man. As flocks of dunlin or redshank stream and wheel and soar and quiver over our estuaries, so above the great tide-flooded cultivated regions of these worlds the animated clouds of avians maneuvered, each cloud a single center of consciousness.
Source: tatoeba (9493512)