From Michael's link:
Now after this withdrawal of Ein Sof (which left an empty space or vacuum in the very center of the light of Ein Sof, as we have said), there remained a place in which there could emerge the things to be emanated, to be created, to be formed and to be made. |
MyJewishLearning.com - Ideas & Belief: God’s Withdrawal
Maybe after Christmas we can talk about this.