The eye (sight) departed, and having been absent for a year, it came back and said: 'How have you been able to live without me?' They replied: 'Like blind people, not seeing with the eye, but breathing with the breath, speaking with the tongue, hearing with the ear, knowing with the mind, generating with seed. Thus we have lived.' Then the eye entered in.

In plain words: Then sight left for a year. The others lived on like blind people, still breathing, speaking, hearing and thinking. So the eye came back in.