Part 11 · Chapter 19

And behold, it is known that our sages, may their memory be blessed, said (Berachot 60) that on the fortieth day the form of the fetus is completed. And the matter is, that after the three days of absorption, in which the 19 sparks of the filling of MA, which is the phase of the life-force of ZA, were subdued, afterward the filling of SAG of Ima enters, which are the 37 sparks. And if you add them to the three days of absorption, it is forty days, when the filling of the 37 of SAG of Ima is completed, which gives the form of the fetus, as is known from the verse, "And the LORD God formed the man" (Gen. 2:7). And for this reason the point of the Tzeirei is also in Ima, as is known. And thus in forty days the form of the fetus is completed, which is the entry of the other 37 sparks of the filling of SAG.