The eye is the intention
This our blessed Lord declares in the liveliest manner, in those strong and comprehensive words which he explains, enforces, and enlarges upon throughout this whole chapter. The light of the body is the eye. If therefore your eye is single, your whole body shall be full of light. But if your eye is evil, your whole body shall be full of darkness (Matthew 6:22-23). The eye is the intention: what the eye is to the body, the intention is to the soul. As the one guides all the motions of the body, so does the other those of the soul. This eye of the soul is then said to be single when it looks at one thing only, when we have no other design but to know God and Jesus Christ whom he has sent (John 17:3), to know him with suitable affections, loving him as he has loved us, to please God in all things, to serve God (as we love him) with all our heart and mind and soul and strength, and to enjoy God in all and above all things, in time and in eternity.
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2. This our blessed Lord declares in the liveliest manner, in those strong and comprehensive words which he explains, inforces and inlarges upon, throughout this whole chapter. The light of the body is the eye. If therefore thine eye be single, thy whole body shall be full of light: but if thine eye be evil, thy whole body shall be full of darkness. The eye is the intention: what the eye is to the body, the intention is to the soul. As the one guides all the motions of the body, so does the other those of the soul. This eye of the soul is then said to be single, when it looks at one thing only; when we have no other design, but to know God, and Jesus Christ whom he hath sent: to know him with suitable affections, loving him as he hath loved us: to please God in all things: to serve God (as we love him) with all our heart and mind and soul and strength: and to enjoy God in all and above all things, in time and in eternity.