What Itell You Three Times Is True

 "Just the place for a Snark!" the Bellman cried,
 As he landed his crew with care;
 Supporting each man on the top of the tide
 By a finger entwined in his hair.
 "Just the place for a Snark! I have said it twice:
 That alone should encourage the crew.
 Just the place for a Snark! I have said it thrice:
 What I tell you three times is true."

http://home.earthlink.net/~lfdean/carroll/snark/fit1.html

---

Contrast SinceWhenDoesSayingSomethingMakeItSo.

Carroll may have intended this line as comic contrast to the long-established Law of Witnesses, namely that an important fact must be established by two or three independent witnesses, not by one witness three times.