Bacon was born in 1214 and died in 1292. By some it is held that
he was not appreciated in his own time because he was really a
modern scientist living in an age two centuries before modern
science or methods of modern scientific thinking were known. Such
an estimate, however, is a manifest exaggeration of the facts,
although there is probably a grain of truth in it withal. His
learning certainly brought him into contact with the great
thinkers of the time, and his writings caused him to be
imprisoned by his fellow-churchmen at different times, from which
circumstances we may gather that he was advanced thinker, even if
not a modern scientist.

Although Bacon was at various times in durance, or under
surveillance, and forbidden to write, he was nevertheless a
marvellously prolific writer, as is shown by the numerous books
and unpublished manuscripts of his still extant. His
master-production was the Opus Majus. In Part IV. of this work he
attempts to show that all sciences rest ultimately on
mathematics; but Part V., which treats of perspective, is of
particular interest to modern scientists, because in this he
discusses reflection and refraction, and the properties of
mirrors and lenses. In this part, also, it is evident that he is
making use of such Arabian writers as Alkindi and Alhazen, and
this is of especial interest, since it has been used by his
detractors, who accuse him of lack of originality, to prove that
his seeming inventions and discoveries were in reality
adaptations of the Arab scientists. It is difficult to determine
just how fully such criticisms are justified. It is certain,
however, that in this part he describes the anatomy of the eye
with great accuracy, and discusses mirrors and lenses.