Philippians 3:13

Brethren, I count not myself to have apprehended
That for which he was apprehended of Christ: he had not attained to perfect knowledge, was not come to the mark, had not received the prize, or laid hold on eternal life; though he had received so much grace, and such gifts, as had qualified him for an apostle; and he had been so many years in that office, and had so great a knowledge in the mystery of the Gospel, and had laboured in it more abundantly than others, and with great success; and even though he had been caught up into the third heaven, and had heard unspeakable words, not lawful to be uttered, ( 2 Corinthians 12:2-4 ) , yet he had no such opinion of himself, as if he was perfect: by which way of speaking, he tacitly strikes at the arrogance and vain confidence of false teachers, that pretended to perfection; and in this way led the brethren to conclude, that they could never have arrived to it, since so great an apostle had not; some copies read not "yet", and so the Ethiopic version:

but this one thing [I do];
which he was intent upon, constantly attended to, and earnestly pursued; it was the main and principal thing he was set upon, and which he employed himself in; and which engrossed all his thoughts, desires, affections, time, and labour; see ( Psalms 27:4 ) ( Luke 10:42 ) . The Syriac version reads, "this one thing I know"; signifying that whatever he was ignorant of, and however imperfect his knowledge was in other things, this he was full well apprized of, and acquainted with. The Arabic version renders the whole thus, "I do not think that I have now obtained and received anything, but the one thing"; namely, what follows;

forgetting those things which are behind,
meaning not the sins of his past life, which were indeed forgotten by God, and the guilt of which was removed from him, by the application of the blood of Christ, so that he had no more conscience of them; yet they were remembered and made mention of by him, partly for his own humiliation, and partly to magnify the grace of God: nor earthly and worldly things, which believers are too apt to have respect to, to look back upon, and hanker after, as the Israelites did after the fleshpots in Egypt, ( Exodus 16:3 ) ; though these were forgotten by the apostle, so as not anxiously to care for them, and seek after them, to set his affections on them, or trust in them: nor his fleshly privileges, and legal righteousness, which he pursued, valued, and trusted in before conversion, but now dropped, renounced, disregarded, and counted as loss and dung, ( Philippians 3:7 Philippians 3:8 ) ; but rather his labours and works of righteousness since conversion, which though he times took notice of for the magnifying of the grace of God, for the defence of the Gospel, and to put a stop to the vain boasting of false teachers, yet he forgot them in point of dependence on them, and trust to them; and having put his hand to the plough, he did not look back, nor desist, but went on in his laborious way, not thinking of what he had done and gone through, nor discouraged at what was before him; as also he intends all his growth in grace, and proficiency in divine knowledge, which was very, great; and though he was thankful for these things, and would observe them to the glory of the grace of God, yet he trusted not in them: nor did he sit down easy and satisfied with what he had attained unto, and therefore was

reaching forth unto those things which are before;
to perfection of knowledge, holiness, and happiness, which were before him, and he as yet had not attained unto; but was desirous of, and pursued after with great vehemence and eagerness; the metaphor is taken from runners in a race, who did not stop to look behind them, and see what way they have run, and how far they are before others, but look and move forwards, and stretch themselves out to the uttermost, and run with all their might and main to the mark before them; and so the apostle did in a spiritual sense.