In this article, I discuss the importance of multidisciplinary research to tackle the questions that empirical sciences, and in particular neuroscience, ultimately encounter. The last decades have witnessed an enormous progress in brain research, mainly because of the improvement of neuroimaging techniques and neurogenetics, and the development of optogenetics. Furthermore, the US Government and European Union have launched the BRAIN Initiative and Human Brain Project, respectively, to promote a better understanding of brain functioning and its disorders. Unfortunately, their gates appear sealed for disciplines that pursue a deep knowledge of the mind, such as philosophy or psychology. The most probable outcome of this situation is "promissory materialism", as Sir John Eccles warned several decades ago. I review the multidisciplinary approach of Eccles to the study of the brain and mind, especially through his relationship with Mariano Artigas. Finally, I propose that interdisciplinary research may be improved by a more solid understanding of the discipline one wants to dialogue with, and a multidisciplinary training from the beginning of the research career.