Targum Pseudo-Jonathan on (Genesis 3:8) uses a phrase it will return to again and again: "the Word of the Lord God" — the Memra, the divine speech as a presence in its own right. Adam and his wife hear the voice of the Memra "walking in the garden in the repose of the day."
The repose of the day — the cool evening — is the hour when, in Eden, God and humanity met. And on this one evening, they hide. The silence tells everything. When the Memra comes, they are not waiting for Him under a tree. They are behind the trees. The garden's geography has changed. Yesterday, every tree was a shelter. Today, the same trees are hiding places.