In his 1866 habilitation thesis Brentano defends Aristotle’s concept of psychology as ‘the science of the soul’, but in his next study Psychology from an Empirical Standpoint (1874) he expounds a ‘modern conception’ of psychology as the natural science of ‘psychical phenomena’. This article argues that although Brentano has become clearly impressed by the rise of the natural sciences, the priority which he attributes to the ‘inner perception of our own psychical phenomena’ as the ‘experiential basis’ for the science of ‘empirical psychology’ in his 1874 study indicates that he is now following a line of enquiry that is advanced from within the tradition of modern philosophical psychology accredited to Descartes and advocated by ‘English empiricists’, such as, Locke, Hume and J.S. Mill, authors whom Brentano read for several years after the completion of his habilitation thesis. This article examines the influence of the ‘English empiricists’ on Brentano’s new understanding of ‘psychology’ and his celebrated discovery of the intentionality of consciousness in his 1874 study, a tenet that is not found in Aristotle or the medieval Aristotelians but one that is found, albeit in embryonic fashion, in those ‘English empiricists’ whom he read.