The spring 2004 issue of Scientific American Mind presented a sampling of the research that attempts to elucidate what makes us us. As readers learned, influences both internal and external create and shape the mind and brain. Researchers have explored the mystery of self through the study of concrete stimuli such as the effects of music and television, abstract issues (including the nature of free will and the power of persuasion) and even the effects of diseases such as autism and anxiety disorders. The editors invited readers to share their reactions to the issue and their resulting insights into the elusive human psyche. A selection of the reader responses appear on the following pages.