John Calvin Commentary Genesis 38:14

"And she put off from her the garments of her widowhood, and covered herself with her veil, and wrapped herself, and sat in the gate of Enaim, which is by the way to Timnah; for she saw that Shelah was grown up, and she was not given unto him to wife." — Genesis 38:14 (ASV)

And sat in an open place. Interpreters explain this passage in various ways. Literally, it is “in the door of fountains, or of eyes.” Some suppose there was a fountain that branched into two streams; others think that a broad place is indicated, where one's eyes can look around in all directions.

But a third interpretation is more worthy of acceptance; namely, that this expression means a way that is forked and divided into two. This is because then, as it were, a door is opened before the eyes, so that those who are actually on one path can diverge in two directions.

Probably it was a place from where Tamar might be seen, near which there was some side road where Judah could turn, so that he would not be guilty of fornication publicly, in plain sight of everyone. When it is said she veiled her face, we infer from this that the freedom to commit fornication was not as unrestrained as that which prevails today in many places.

For she dressed herself in the manner of harlots, so that Judah would suspect nothing. And the Lord has caused this sense of shame to remain engraved on the hearts of those who live wickedly, so that they may be witnesses to themselves of their own vileness. For if people could wash away the stains of their sins, we know that they would do so most willingly. From this it follows that while they flee from the light, they are affected with horror against their will, so that their conscience anticipates the judgment of God.

Gradually, indeed, most people have gone to such extremes of stupor and impudence that they are less careful about hiding their faults; yet God has never allowed the natural moral sense to be so completely extinguished by the brutal intemperance of those who desire to sin with impunity, but that their own obscenity still compels even the most wicked to be ashamed. Therefore, base was the impudence of that cynic philosopher who, being caught in vice, boasted of planting a person. In short, the veil of Tamar shows that fornication was not only a base and filthy thing in the sight of God and the angels, but that it has also always been condemned, even by those who have practiced it.