I've always thought of a tautology as "something that defines itself," which is a bit more than the dictionary definition of "redundancy."
It's the kissing cousin of paradox, I feel, "a seemingly contradictory statement which may nonethelss be true."
And I strongly believe that many of the great truths in life are paradoxical.
Anyway, here's the inspiration for the above, a working definition of love that has served me well in my spiritual growth:
“I define love thus: The will to extend oneself for the purpose of nurturing one’s own or another’s spiritual growth.”
– M. Scott Peck, The Road Less Traveled (P. 81)
Now click here for something apropos: