In the present study [1], we wish to investigate the problem of development in structural psychology. The aim of this investigation is to separate what is genuine from what is false in this theory. We will approach this goal following a path that has been tested repeatedly. We will rely in our investigation upon what is true in this theory, and with its help we will lay bare the false premises that obscure it, for according to Spinoza's [1677/1955, p. 115] great idea the truth displays both itself and falsity. [2]