My own field, sleep and dream research, affords abundant examples. One of the most striking and relevant recent discoveries is that the localization of stroke lesions can be correlated with changes in dreaming. Mark Solms (1), a psychoanalytically oriented neuropsychologist, studied 300 cases of stroke and found that dreaming is suppressed and/or permanently eliminated by stroke damage to the parietal operculum or to frontal white matter. Now, these findings could have been made at any time, by any neurologist (including Sigmund Freud), but they were not. Why not? The reason is clear. Sleep and especially dreaming were not taken into account by neurology, but they were of great interest to psychiatry.