This chapter is about how and why Bion chose the relatively unknown British philosopher of science R.B. Braithwaite as one of the primary sources in his search to establish a scientific basis to his rapidly developing theoretical work. We discuss what Bion was attempting to understand about the nature of science and describe how Bion’s reading and understanding of Braithwaite helped him to develop the significant concepts that underlay his own theories. The British psychoanalytical movement, during the period between about 1950 to 1970, was undergoing massive internal upheavals, characterized by great problems in communication not only within the movement but also in relation to the external context. The golden years of psychoanalysis were beginning to come to an end. Bion, a central figure in the British Psychoanalytical Society and a renowned analyst in his own right, turned his mind to the bases of clinical and theoretical problems. The development of Bion’s theoretical work, which was markedly influenced by Braithwaite, both shaped and in turn was influenced by his extensive experience of clinical practice specifically, Braithwaite contributing theoretically towards his attempts to systematize and understand the clinical process of psychoanalytic sessions. This chapter explores and discusses the problems that Bion was attempting to address and suggests why and how Braithwaite, was a major influence on his thinking. We also reflect on the outcome of this project to place psychoanalysis on a more ‘scientific’ basis.