This article is from the alt.usage.english FAQ, by Mark Israel firstname.lastname@example.org with numerous contributions by others.
E-prime is a subset of standard idiomatic English that eschews
all forms of the verb "to be" (e.g., you can't say "You are an ass"
or "You an ass", but you can say "You act like an ass"). The
original reference is D. David Bourland, Jr., "A linguistic note:
write in E-prime" "General Semantics Bulletin", 1965/1966, 32 and
33, 60-61. Albert Ellis wrote a book in E-prime ("Sex and the
Liberated Man"). You can also look at the April 1992 issue of the
"Atlantic" if you're interested. (We're not.) The following book
contains articles both pro and con on E-Prime: "To Be or Not: An
E-Prime Anthology", ed. D. David Bourland and Paul D. Johnston,
International Society for General Semantics, 1991, ISBN
0-918970-38-5. The most pertinent Web page seems to be