518. Why, when we move before a mirror, does the image draw near to the reflecting surface as we draw near to it, and retire when we retire?
Because the lines and angles of reflection are always equal to the lines and angles of incidence.
519. What is the line of incidence?
If a person stands in a direct line before a mirror, the line through which the light travels from him to the mirror is the line of incidence.
Incidence—falling on.
"Blessed be the Lord, who daily loadeth us with benefits, even the God of our salvation."—Psalm lxviii.