The word rendered "knowledge" means "mature knowledge," and is one of the characteristic words of these four Epistles written from Rome. The Apostle evidently regarded mature knowledge, or deep spiritual experience, as the pre-eminent mark of a ripening Christian. In this respect St. John bears the same testimony, in his reference to the three stages of the Christian life represented by "little children," "young men," and "fathers." The little children _have_; the young men _are_; the fathers _know_ (1 John ii. 12-14). This spiritual knowledge or experience is the great safeguard against error, in that it gives power to distinguish between good and evil, between truth and falsehood. The measure of this knowledge is to be carefully noted--"_filled with_ the knowledge of His will." The word also implies a fulness which is realised continually--not a bare knowledge, but its completeness; not an intermittent stream, but a perpetual flow. When the soul experiences this it is provided not only with the greatest safeguard against danger, but also with the secret of a strong, growing, powerful Christian life. The characteristics of this knowledge should be observed: "_In all wisdom and spiritual understanding_." "Wisdom" is a general term which implies the capacity and faculty for adapting the best means to bring about the best ends in things spiritual. "Spiritual understanding" is the specific coming or putting together of principles by means of which true action is taken. It really means "putting two and two together," comparing ideas and principles, for the purpose of adopting the best in any given course of action. Of the importance and necessity of wisdom and spiritual understanding scarcely anything need be said. Christian wisdom, Christian understanding, Christian perception in the thousand and one things of life--this surely is one of our greatest necessities and choicest blessings. How many errors would be avoided, how many wanderings checked, by means of this spiritual wisdom! Still more, how much joy would be experienced and how much genuine service rendered, if we were always saying and doing the right thing, at the right time, in the right way.