There is a line in Saint-Exupery's "The Little Prince" that applies to any endeavor, but especially teaching. It reads: "That which is essential cannot be seen with the eye. Only with the heart can one know it rightly." The essence of teaching is difficult to qualify, but that line leads directly into the author's most essential criterion. In this article, the author discusses ten characteristics of a good teacher which can be separated into four areas: (1) affective characteristics; (2) skills; (3) classroom management techniques; and (4) academic knowledge. (Contains 1 footnote.) [This article was first published in Volume 25, No. 1 (1987).]