A coast means a boundary line such as divides one territory from another, or terminates a country, as the sea coast is the boundary of our island. Every quickened soul has a coast; that is, a territory of inward experience, which is limited and bounded by the line that the Holy Spirit has drawn in his conscience.
As the Lord divided the tribes, to cast their inheritance by line (Psalm 78:55), so hath he cast the lot for every vessel of mercy, and his hand hath divided it unto them by line (Isaiah 34:17). This is as it were the tether which fastens down every quickened soul to his own appointed portion of inward experience. Within this tether he may walk, feed, and lie down. It is "the food convenient for him," the strip of pasture allotted him. He cannot, he dare not break this tether, which is fastened round a tender conscience, and every stretching forth beyond his measure to boast in another man's line of things, cuts into and galls this tender conscience.
But the living soul cannot but earnestly desire to have his coast enlarged. He wants more light, more life, more feeling, more liberty, more knowledge of God in Christ, more faith, hope, and love, and to have his narrow, contracted, shut-up heart enlarged in prayer, in meditation, in communion, in affection to the people of God. He is not satisfied with the scanty pasture allotted him, but wants a larger measure of heavenly teaching, to be indulged with more filial confidence in, and access unto God, and be more delivered from that fear which hath torment.
"God shall enlarge Japheth, and he shall dwell in the tents of Shem" (Gen. 9:27). "I will run the way of thy commandments, when thou shalt enlarge my heart" (Psalm 119:32). This enlargement of their border the Lord had sworn to Israel, and to give them all the land which he had promised unto their fathers; and therefore when he had said, "Sing, O barren, thou that didst not bear," he adds, "enlarge the place of thy tent, and let them stretch forth the curtains of thy habitations; spare not, lengthen thy cords, and strengthen thy stakes" (Isaiah 54:1, 2).
Have you any of these fervent desires after light, love, and liberty, that the world, pride, lust, unbelief, covetousness, and carnality may not shut up your heart, but that you may know the love of Christ that passeth knowledge, so as to be filled with all the fulness of God? These are good desires, and very different from rushing presumptuously forward, and chattering about liberty whilst you are slaves of corruption.
It is one thing to look through the park palings, and another to enjoy the estate; but it is far better to look through the palings with wishful desires, than to break down the fence as a trespasser. To look upon the coffer is not to be put into possession of the writings, but it is better to wait and cry for the key of David than break it open, and steal the deeds. And he that is kept in the narrow, narrow path between sloth and presumption will be at solemn seasons crying out with Jabez, "O that thou wouldest enlarge my coast!"