Whittle has written an incisive and often witty exploration of the ways to answer the question posed in his title. Essentially he tells us to “mind the gap,” an expression familiar to London Underground passengers that warns them to avoid stepping into the space between train and platform. But Whittle is doing more than warning us about the “gap” between experimental psychology and psychoanalysis, he wants us to understand why there is a gap, and if it is worth closing, or if the gap itself constitutes a potentially fruitful divergence between the two fields.