This paper focuses on molarity, ecological validity, objectivity, vicarious functioning, and the historical roots of ethology as developed by Konrad Lorenz and Niko Tinbergen. Some of their views are shown to go back to the ideas of Karl Bühler and another of his students, Egon Brunswik, as well as a one-time visitor of Bühler and Brunswik in Vienna, E. C. Tolman. Especially Bühler’s views on Gestalt, the emphasis on the functional interaction between organism and its environment, and the relation to Bühler’s ‘organon theory of language’ are discussed. The ideas of molarity and Gestalt have found a place in ethology as a new way of explaining behaviour in biology (as an alternative to zoology or physiology in the biology of the 1930s). Bühler’s theory of the multiple role of signs (as a symptom, signal and symbol) in language found its way into Brunswik concept of vicarious functioning and his ‘lens model’, as well as into Tinbergen’s views on the ‘aims and methods of ethology’.