Four stories by an SF specialist should be welcomed by the space-hardened for they develop the colonizing of new worlds, the possibility of friendliness between alien cultures and the coexistence of unfamiliar peoples. The title story deals with the Martian community's need for water; Youth wins gentleness from Arcturians; The Deep has below surface dwellers penetrating others' minds for survival; Sucker Bait proves a mnemonic wizard a hero when he saves an expedition from a killer planet. Snappy.