John Calvin Commentary Psalms 139:16

"Thine eyes did see mine unformed substance; And in thy book they were all written, [Even] the days that were ordained [for me], When as yet there was none of them." — Psalms 139:16 (ASV)

Your eyes beheld my shapelessness, etc. The embryo, when first conceived in the womb, has no form; and David speaks of God having known him when he was still a shapeless mass, τὸ κύημα, as the Greeks term it; for τὸ ἔμβρυον is the name given to the fetus from the time of conception to birth inclusive.

The argument is from the greater to the less. If he was known to God before he had grown to a certain definite shape, much less could he now elude His observation. He adds that all things were written in His book; that is, the whole method of his formation was well known to God.

The term book is a figure taken from the practice common among people of helping their memory by means of books and commentaries. Whatever is an object of God’s knowledge, He is said to have registered in writing, for He needs no helps to memory. Interpreters are not agreed as to the second clause.

Some read ימים, yamim, in the nominative case, when days were made; the sense being, according to them—All my bones were written in Your book, O God! from the beginning of the world, when days were first formed by You, and when as yet none of them actually existed.

The other is the more natural meaning: that the different parts of the human body are formed in a succession of time; for in the first germ there is no arrangement of parts or proportion of members, but it is developed and takes its peculiar form progressively. There is another point on which interpreters differ.

As in the particle לא, lo, the א, aleph, is often interchangeable with ו vau; some read לו , to him, and others לא not.

According to the first reading, the sense is that even though the body is formed progressively, it was always one and the same in God’s book, for He is not dependent on time for the execution of His work.

A sufficiently good meaning, however, can be obtained by adhering without change to the negative particle. This interpretation holds that even though the members were formed in the course of days, or gradually, none of them had existed at first; no order or distinctness of parts was present initially, only a formless substance.

And thus our admiration is directed to the providence of God in gradually giving shape and beauty to a confused mass.