There is implied here a view of human nature, not flattering but true. It is compared with a dead thing, in which the causes that bring about corruption are already at work, with the sure issue of destruction. This in its individual application comes to the assertion of sinful tendency and actual sin as having its seat and root in all our souls, so that the present condition is corruption, and the future issue is destruction. The consequent ideas are that any power which is to cleanse must come from without, not from within; that purity is not to be won by our own efforts, and that there is no disposition in human nature to make these efforts. There is no recuperative power in human nature. True, there may be outward reformation of habits, etc., but, if we grasp the thought that the taproot of sin is selfishness, this impotence becomes clearer, and it is seen that sin affects all our being, and that therefore the healing must come from beyond us.
(b) The purpose—namely, cleansing.
In salt we may include the whole divine energy; the Word, the Christ, the Spirit. So the intention of the Gospel is mainly to make clean. Preservation is a consequence of that.
(c) The manner of its application.
Inward, penetrating, by contact; but mainly the great peculiarity of Christian ethics is that the inner life is dealt with first, the will and the heart, and afterwards the outward conduct.
II. The part which we have to take in this cleansing process.
'Have salt' is a command; and this implies that while all the cleansing energy comes from God, the working of it on our souls depends on ourselves.
(a) Its original reception depends on our faith.
The 'salt' is here, but our contact with it is established by our acceptance of it. There is no magical cleansing; but it must be received within if we would share in its operation.
(b) Its continuous energy is not secured without our effort.