The early origin of the telescope, like that of most other important inventions, is lost in obscurity, and it is now impossible to determine who was the first maker. It is certain that some time prior to the end of the 13th century lenses were in common use for assisting in procuring distinctness of vision. A certain Vitello, a native of Poland, seems to have done something in this line; and Eoger Bacon, in one of his works, employs expressions which show that even in his time (he died in 1292), spectacles were known.

Seeing that this was the case, it is almost certain that some combination of 2 or more lenses must have been made in the interval which elapsed between Bacon's time and the commencement of the 17th century, when telescopes are usually considered to have been invented. Dr. Dee mentions that though some skill is required to ascertain the strength of an enemy's force, yet that the commander of an army might wonderfully help himself by the aid of “perspective glasses,” a phrase which must refer to some kind of optical instrument then in use