Remember that the eye allows the light to enter our mind and our very soul; hence, if it is single to the glory of God (see D&C 4:5), our whole body will be filled with light (D&C 88:67) and we will comprehend all things. If not, we are left in darkness. “While one’s eye is to be single to His glory, we must remember that His glory is to bring to pass the immortality and eternal life of man” (Neal A. Maxwell, Plain and Precious Things [Salt Lake City: Deseret Book, 1983], 27).