See
also Targum Neophyti Gen 25:27. Rachi writes that Jacob "is a plain
man," and comments "He is not expert in all these (worthless pursuits),
as is his heart (mind) so is his mouth. One who is not sharp minded in deceiving
is called tâm (plain)," Rabbi Abraham Ben Isaiah and Rabbi
Benjamin Sharfman, The Pentateuch and Rashi's Commentary: A Linear Translation
into English, S. S. & R. Publishing Company: Brooklyn, N.Y., 1976, p.
244.