Lambda as a symbol of gay/lesbian rights

The Encyclopedia of Homosexuality has the following entry on Lambda:

In the early 1970s, in the wake of the Stonewall Rebellion, New York City's Gay Activists Alliance selected the Greek letter lambda, which member Tom Doerr suggested from its scientific use to designate kinetic potential, as its emblem. (Curiously, in some ancient Greek graffiti the capital lambda appears with the meaning fellate, representing the first letter of either lambazein or laikazein.) Because of its militant associations, the lambda symbol has spread throughout the world. It sometimes appears in the form of an amulet hung round the neck as a subtle sign of recognition which can pass among unknowing heterosexuals as a mere ornament. Such emblems may reflect a tendency among homosexuals toward tribalization as a distinct segment of society, one conceived as a quasi-ethnic group.

In More Man Than You'll Ever Be by Joseph P. Goodwin (Indiana University Press:Bloomington, 1989) on page 26, Goodwin writes:

The lowercase Greek letter lambda carries several meanings. First of all, it represents scales, and thus balance. The Greeks considered balance to be the constant adjustment necessary to keep opposing forces from overcoming each other. The hook at the bottom of the right leg of the lambda represents the action required to reach and maintain a balance. To the Spartans, the lambda meant unity. They felt that society should never infringe on anyone's individuality and freedom. The Romans adopted the letter to represent "the light of knowledge shed into the darkness of ignorance." Finally, in physics the symbol designates and energy change. Thus the lambda, with all its meanings, is an especially apt symbol for the gay liberation movement, which energetically seeks a balance in society and which strives through enlightenment to secure equal rights for homosexual people.