The whole shall be full of light - Or, altogether enlightened; i.e. when the eye is perfect, it enlightens the whole body. Every object within the reach of the eye is as completely seen as if there was an eye in every part. So the eye is to every part of the body what the lamp is to every part of the house.

When the light of Christ dwells fully in the heart, it extends its influence to every thought, word, and action; and directs its possessor how he is to act in all places and circumstances. It is of the utmost importance to have the soul properly influenced by the wisdom that comes from above. The doctrine that is contrary to the Gospel may say, Ignorance is the mother of devotion; but Christ shows that there can be no devotion without heavenly light. Ignorance is the mother of superstition; but with this the heavenly light has nothing to do.

If thy whole body therefore be full of light,.... That is, if the whole soul, as the Ethiopic version reads, be full of Gospel light, through the illuminating influences of the blessed Spirit accompanying the word:

having no part dark; every power and faculty of the soul being affected with it, and influenced by it, though, as yet, the light and knowledge of evangelical things is not perfect in any:

the whole shall be full of light, as when the bright shining of a candle doth give thee light; the whole soul shall be as full of light and joy, which the Gospel always brings with it, as a room is full of light, when a candle is lighted, and shines brightly, and burns clearly in it.

The bright shining of a candle (ὁ λύχνος τῇ ἀστραπῇ)

More correctly, as Rev., the lamp with its bright shining. Ἀστραπή means lightning: see Luke 10:18; and that is the usual meaning in classical Greek, though it occurs, rarely, of the light of a lamp. It is used here to emphasize the idea of moral illumination.

If thy whole body therefore be full of light, having no part dark, the whole shall be full of light, as when the bright shining of a candle doth give thee light.

11:36 If thy whole body be full of light - If thou art filled with holy wisdom, having no part dark, giving way to no sin or folly, then that heavenly principle will, like the clear flame of a lamp in a room that was dark before, shed its light into all thy powers and faculties.

the bright...: Gr. a candle by its bright shining

11:29-36 Christ promised that there should be one sign more given, even the sign of Jonah the prophet; which in Matthew is explained, as meaning the resurrection of Christ; and he warned them to improve this sign. But though Christ himself were the constant preacher in any congregation, and worked miracles daily among them, yet unless his grace humbled their hearts, they would not profit by his word. Let us not desire more evidence and fuller teaching than the Lord is pleased to afford us. We should pray without ceasing that our hearts and understandings may be opened, that we may profit by the light we enjoy. And especially take heed that the light which is in us be not darkness; for if our leading principles be wrong, our judgment and practice must become more so.