Bion's theories, which were always based in the phenomena of the analytic encounter, revealed both correspondences and expansions of core ideas from both Sigmund Freud and Melanie Klein. At one point, he attempted to understand thoughts and thinking from an 'algebraic', 'geometric' and 'mathematised' point of view, believing there to be too little precision in the existing vocabulary, a process culminating in "The Grid". Later he abandoned the complex, abstract applications of mathematics, and the Grid, and developed a more intuitive approach, epitomised in "Attention and Interpretation" (1970).