Grammatical Tautology.

I’ll prove the word that I’ve made my theme,
Is that that may be doubled without blame ;
And that that that, thus trebled, I may use,
And that that THAT that critics may abuse,
May be correct. Farther—the dons to bother—
Five THATs may closely follow one another !
For be it known that we may safely write
Or say, that that THAT that that man wrote was right :
Nay, e’en, that that THAT that THAT that followed ;
And that that THAT (that that THAT that began)
Repeated seven times is right !—Deny’t who can.

Scientific American: New York, November 28, 1846.

cf. That.