There is a famous couplet in the Tao Te Ching that runs:

He who knows does not speak.
He who speaks does not know.

This is encompased in two lines of four characters each in Classical  
Chinese, roughly:

know * he who * not * speak
speak * he who * not * know

In Modern Irish this gets a little wordy:

An té a bhfuil a fhios aige, ní labhraíonn sé.
An té a labhraíonn, níl a fhios aige.

Old Irish, on the other hand, is often wonderfully concise.  Do the  
verbs "in·gnin" and "labraithir" fill the bill for "know" and "speak"?

Int í in·gnin, ní·labrathar.
Int í labrathar, ní·ingéuin.

Does that work?   Can we regularize the Ml. spelling "ingéuin"?

Dála an scéil, am ar bith a fheicim an focal "ineffable", ba mhaith  
liom é a mhíniú mar "cannot be fucked with".