It is a commanded duty, that we grow in the knowledge of Jesus Christ, 2 Pet. iii. 18; and the knowledge of him being life eternal, John xvii. 3, and our measure of knowledge of him here being but imperfect, for we know but in part, it cannot but be an useful duty, and a desirable thing, to be growing in this knowledge. This is to walk worthy of the Lord unto all pleasing, to be increasing in the knowledge of God, Col. i. 10. Knowledge must be added to virtue; and it layeth a ground for other Christian virtues, 2 Pet. i. 5, 6. In this knowledge we must not be barren, 2 Pet. i. 2. And this being so necessary, so desirable, so useful, and so advantageous a grace, the believer cannot but desire to have more and more of it, especially seeing it is a part of the image of God, Col. iii. 10. Now it is the truth that must teach them here, first and last. "The light of the knowledge of the glory of God must be had in the face of Jesus Christ," 2 Cor. iv. 6. The question therefore is, how we should make use of Jesus Christ for this end, that we may attain to more of this excellent knowledge. _First._ It is good to live in the constant conviction of a necessity of his teaching us, and this taketh in those particulars: 1. That we should be conscious of our ignorance, even when we know most, or think we know most, remembering that the best knoweth but in part, 1 Cor. xiii. 9. The more true knowledge we attain to, the more will we see and be convinced of our ignorance; because the more we know, the more will we discover of the vastness and incomprehensibility of that object, which is proposed to our knowledge. 2. That we should remember, how deceitful our hearts are; and how ready they are to sit down upon a shadow of knowledge, even where we know nothing as we ought to know, 1 Cor. viii. 2; and this will keep us jealous and watchful. 3. And to help forward our jealousy of our own hearts and watchfulness, we should remember that our hearts naturally are averse from any true and saving knowledge; whatever desire there be naturally after knowledge of hidden things out of curiosity; and of things natural; or of things spiritual, as natural, for the perfection of nature, as might be pretended, whereby in effect those that increase knowledge, increase sorrow, Eccl. i. 18. Yet there is no inclination after spiritual and saving knowledge, in us naturally, but an aversion of heart therefrom. 4. That we should study and know the absolute necessity of this knowledge. How necessary it is for our Christian communion with God, and Christian walk with others; how necessary for our right improving of dispensations, general and particular; what a noble ornament of a Christian it is, and a necessary piece of the image of God, which we have lost. _Secondly._ Upon these grounds mentioned, we would also be convinced of this: