। ॥ १६८ ॥
In plain words
A mirror thick with grime, scrubbed a long while with ash, comes clean — and then your face stands in it, sharp and bright. Clean the mind that way, and jñāna appears in it just so.
Close to the Sanskrit
Just as, in a stained mirror cleaned for a long time with ash and the like, the face is reflected vividly — so too, in a purified mind, knowledge.