But al thyng which that shineth as the gold Nis nat gold, as that I have herd told. Modern English: However, all that glitters is not gold, And that's the truth as we're so often told.

But al thyng which that shineth as the gold
Nis nat gold, as that I have herd told.
Modern English:
However, all that glitters is not gold,
And that’s the truth as we’re so often told.

– Geoffrey Chaucer

The Canterbury Tales, The Canon’s Yeoman’s Tale. The Yeoman refers to the dubious practice of alchemy, but also the trickery and deceptions people sometimes practice.

Geoffrey Chaucer Quotes