At whatever period these pictures of nature were laid up in the memory of Isaiah, they came back to him when he was engaged in the work of a prophet, and supplied the imagery by means of which the Divine truths which he heralded were made impressive and attractive to his countrymen and acceptable to all subsequent generations; for men are so made that they are never so won by the truth as when they see it reflected in a physical image.
These two sides of the prophet's activity nearly correspond to what we should call Thought and Expression. Or, to put it still more broadly, the preacher must be a man who both has something to say and knows how to say it. On these two apparently simple qualifications hang all the science and art of our vocation.
In reality they are not simple. To have the right thing to say is a great commandment, and to know the right way to say it is, though second to it, hardly inferior. But the problem of the ministry is to have both in perfect equipoise--to utter a word which is at the same time both a message from God and a message to men.
It would be possible to be so taken possession of by the message from God as to lose self-control and even reason itself. In Scripture we meet with manifestations of prophecy which are akin to madness. Just as the wind, catching the sail, would, if the ropes were not adjusted to relieve the strain, overturn the boat, so the Wind of God might sweep the mind off its balance, the human personality being overborne by the inrushing inspiration. Thus religion may make a man a fanatic, who has no control over his own spirit, and no wisdom to choose the times at which to speak or the terms in which to address his fellow-men. On the other hand, the opposite excess is still more easy. So much stress may be laid on the form of words, and so much mastery obtained of the art of winning attention, that the necessity of having a Divine message to deliver or of depending on the power of the Spirit of God is forgotten. The windy master of words, whose own spirit is not subdued either by the impression of great thoughts or the sense of a great responsibility, but who can draw the eyes of men on his own performances and earn the incense of applause, has always been too familiar a figure in religion. It is to a man like Isaiah we must look for the absolute balance of both sides. There you have the blowing in all its degrees of the Wind of God, from the gentlest whisper to the force of the tempest, but, at the same time, the most perfect self-control and the adaptation of the word to the tastes and necessities of those to whom it was delivered.
There is a name sometimes applied by the prophets to themselves which admirably expresses the combination and balance of these two aspects of their activity. They call themselves Interpreters. The process of interpretation is a most interesting one, when it is well done. I have heard a speaker address with the greatest fervour a multitude who did not understand a word he was saying; but, as fast as the sentences fell from his lips, another speaker by his side caught them up and, in tones as fervid and with gestures as dramatic as his own, rendered them to the hearers in their own tongue with such effect that the performance made all the impression of an original speech. An interpreter is one who receives a message for people in a language which they do not understand and delivers it to them in their own tongue. Jehovah was incessantly speaking to His people in the vicissitudes of their history, but they did not apprehend His meaning. The prophet, however, understood; he took the Divine message into his own soul, and then he went and communicated it to the people in terms with which they were familiar. An interpreter requires to know at least two languages--that in which the message comes and that in which it has to be delivered. If he knows either imperfectly, his interpretation will be proportionately imperfect. No interpreter of God, perhaps, knows both languages equally well. Some know the Divine language imperfectly, while they know thoroughly the language of men. What they say is interesting, fresh and human; but there is not much of a Divine message in it. Others have got far into the secret of God and know the Divine language well; but they are not sufficiently masters of the language of men. These are saintly men and command reverence by their character, but what they say does not find its way to men's business and bosoms.