I. The meaning which a reader of the English only would affix to these words, amounts to this that on the state of the heart depends the character of the man. The issues of life, the various ends at which a man is landed, the total of what he is in principle or feeling, the value at which Omniscience would sum him up this depends not on external circumstances, but on his heart. Purify, then, and elevate that heart, keep it above all keeping, as a tender plant to be nursed and guarded in an unkindly soil.
II. If we give to these words an interpretation which accords more exactly with the force of the original, they will then mean, that from the heart is the fountain or source of life in the sense of happiness. In this sense the words mean that contentment and happiness in this life depend upon the heart, not upon external circumstances. (1) Observe the difference between the man who is blessed with a cheerful and hopeful heart, and the one who has a desponding and complaining heart not the heart-sickness only which comes of hope deferred, but the heart-jaundice which turns hope itself into despair. While the cheerful heart can find happiness even under circumstances the most depressing, the complaining heart will turn even the most encouraging into misery. (2) Look at the dependence of happiness on tenderness and kindness of heart. Is it too much to say that the man of hard and cruel heart is in the end far more cruel to himself than he can be to anyone else? In himself he tears out by the roots the plant of happiness and dries up at its very springs the "fountain of life."
III. Let the issues of life, which are said to spring from the heart, be those of eternal life, and then the words will mean, that on the state of the heart depends the salvation of the soul.
A. Blomfield, Sermons in Town and Country,p. 193.
I. Inasmuch as "out of the heart are the issues of life" it is important to keep the reservoir full. It is bad enough to have an empty head, but an empty heart is worse still. For, other things being equal, a man's force in the world is just in proportion to the fulness of his heart.
II. Strive with all diligence to keep the heart pure. A full reservoir is not enough; the water must be clean. If the heart be not pure, you may be certain the thoughts will not be pure, nor the conversation, nor the life.
III. Keep your heart tranquil; seek to have a soul calm and peaceful and at rest. You are all but certain to meet with troubles. Most likely some of you will get sadly knocked about in the world, you will meet with reverses and disappointments, but a heart that is fixed on God can bear all these things with equanimity.
J. Thain Davidson, The City Youth,p. 213.
References: Proverbs 4:23. Spurgeon, Sermons, vol. iv., No. 179; Plain Sermons by Contributors to " Tracts for the Times," vol. ix., p. 324; E. M. Goulburn, Thoughts on Personal Religion, p. 218; J. Vaughan, Children's Sermons, 1875, p. 205; Preacher's Monthly, vol. vii., p. 191; R. Tuck, Christian World Pulpit, vol. v., p. 132; Forsyth Hamilton, Pulpit Parables, p. 24.