John Calvin Commentary Genesis 15:12

"And when the sun was going down, a deep sleep fell upon Abram; and, lo, a horror of great darkness fell upon him." — Genesis 15:12 (ASV)

A deep sleep fell upon Abram. The vision is now mingled with a dream. Thus, the Lord here joins those two kinds of communication together, which I have previously related from Numbers 12:6, where it is said:

When I appear unto my servants the prophets,
I speak to them in a vision or a dream.

A vision has already been mentioned; Moses now relates that a dream was also added. A horrible darkness intervened so that Abram might know that the dream was not a common one, but that the whole was divinely guided. Nevertheless, it has a correspondence with the oracle present at that time, as God immediately afterwards explains in his own words, Thou shalt surely know that thy seed shall be a stranger, etc.

We have said elsewhere that God was not accustomed to dazzle the eyes of his people with bare and empty specters, but that in visions, the principal parts always belonged to the word. Thus, here, not a silent apparition is presented to Abram’s eyes, but he is taught by an accompanying oracle what the external and visible symbol meant.

It is, however, to be observed that before one son is given to Abram, he hears that his seed will be in captivity and slavery for a long time. For this is how the Lord deals with his own people: he always makes a beginning from death, so that by quickening the dead, he more abundantly manifests his power.

It was necessary, in part for Abram’s sake, that this should be declared; but the Lord was chiefly concerned for his posterity, lest they should lose heart in their sufferings, for which, however, the Lord had promised a joyful and happy outcome, especially since its long duration would produce great weariness.

And three things are, step by step, brought before them:

1. That the sons of Abram must wander for four hundred years before they would attain the promised inheritance.
2. That they would be slaves.
3. That they were to be inhumanly and tyrannically treated.

Therefore, Abram’s faith was admirable and exceptional, seeing that he accepted such a sorrowful oracle and felt assured that God would be his Deliverer after his miseries had reached their greatest height.

However, the question is asked, how does the number of years given here agree with the subsequent history? Some begin the computation from the time of his departure from Haran. But it seems more probable that only the intermediate time is indicated, as if God would say, ‘Your descendants must wait patiently, because I have not decreed to grant what I now promise until the four hundredth year; indeed, up to that very time their servitude will continue.’

According to this way of reckoning, Moses says (Exodus 12:40) that the children of Israel lived in Egypt four hundred and thirty years. Yet, from Genesis 6:1, we can easily gather that not more than about two hundred and thirty years passed from the time Jacob went down there until their deliverance.

Where then, shall we find the remaining two hundred years, except by referring to the oracle? All doubt on this matter is removed by Paul, who (Galatians 3:17) reckons the years from the gratuitous covenant of life to the promulgation of the Law. In short, God does not indicate how long the people’s servitude would be from its beginning to its end, but how long he intended to suspend or defer his promise.

As for omitting the thirty years, it is neither new nor infrequent, when years are not accurately computed, to mention only the larger sums. But we see here that, for the sake of brevity, the whole of that period is divided into four centuries. Therefore, there is no absurdity in omitting this short period of time. This is chiefly to be considered: that the Lord, to exercise the patience of his people, suspends his promise for more than four centuries.