How dark was it in the labyrinth?

From the text:

A wild and plaintive cry escaped my lips. On earth during the most profound and comparatively complete darkness, light never allows a complete destruction and extinction of its power. Light is so diffuse, so subtle, that it permeates everywhere, and whatever little may remain, the retina of the eye will succeed in finding it. In this place nothing—the absolute obscurity made me blind in every sense.