Here, we learn Adam knew Eve, which is the Bible's way of saying they knew one another in the act of sex. As an aside, this should be instructive concerning sex. To God, sex isn't the mere collision of bodies who are out for a good time. Instead, though it should be clear, because of the design of our sexual organs, that God designed sex to be intensely pleasurable, he always thought of it as a major expression of an intimate relationship. A married couple is to know one another. (10 Minutes/3000 Words)