In the first part, Cytowic describes his chance encounter during a dinner party on February 10, 1980 with MW, the "Man Who Tasted Shapes."

In order to explore the biological basis of synesthesia, Cytowic describes experiments in which he tested how MW's synesthesia was reduced by MW's daily routine of stimulants such as nicotine and caffeine and depressants such as alcohol.

[3] In more intensive investigations of the effects of different psychoactive substances, Cytowic notes that stimulants, including a dose of amphetamine, decreased the strength of MW's synesthesia, while amyl nitrite increased the strength of MW's synesthesia.

[5] Cytowic also summarizes work done with functional neuroimaging which showed unusually low cortical activation in MW.

[9] In the second part of the book, entitled "Essays on the Primacy of Emotion", Cytowic presents a number of his reflections on what the phenomenon of synesthesia means for traditional neuroscientific and neurological practice, how anomalous findings can lead to major scientific discoveries, and the role that emotion plays in our understanding of the world around us.