John Calvin Commentary Genesis 15:17

"And it came to pass, that, when the sun went down, and it was dark, behold, a smoking furnace, and a flaming torch that passed between these pieces." — Genesis 15:17 (ASV)

Behold, a smoking furnace. Again a new vision was added to confirm his faith in the oracle. At first, Abram was horror-struck by the thick darkness; now, in the midst of a smoking furnace, he sees a burning lamp. Many suppose that a sacrifice was consumed by this fire, but I rather interpret it as a symbol of future deliverance, which would agree well with the fact itself.

For there are two things contrary to each other in appearance: the obscurity of smoke and the shining of a lamp. Therefore, Abram knew that light would eventually emerge out of darkness. An analogy is always to be sought between signs and the things signified, so that there may be a mutual correspondence between them.

Then, since the symbol, in itself, is but a lifeless carcass, reference should always be made to the word which is connected to it. But here, by the word, liberty was promised to Abram’s seed, in the midst of servitude. Now the condition of the Church could not be portrayed more vividly than when God causes a burning torch to proceed out of the smoke, so that the darkness of afflictions may not overwhelm us, but that we may cherish a good hope of life even in death, because the Lord will at last shine upon us, if only we offer up ourselves in sacrifice to Him.