Jonathan Swift is one of the most celebrated satirist writers in literature. His well-known "Gulliver's Travels", apart from being a serious human being criticism, contains many interesting ana unrecognized comments about medical and other scientific facts. Swift made what seems to be the first account of a dementing illness in the elderly; his description fits well with what we now know as Alzheimer's disease. He also described a condition now called synaesthesia, a very interesting phenomenon that may contribute to creativity. In this paper, we review aspects of his life and reveal these amazing descriptions as samples of Swift's extraordinary power of observation.