Light being that which discovers to us visible objects, we give the name of OBSCURE to that which is not placed in a light sufficient to discover minutely to us the figure and colours which are observable in it, and which, in a better light, would be discernible.
Argia objektu ikusgarriek erakusten digutena denez, objektu batean ikus daitezkeen irudia eta koloreak zehatz-mehatz ikusteko adinako argitan ez dagoenari eta argipe hobean bereizgarri litzatekeenari iluna deitzen diogu.