And She is called lulav (palm-shoot), from the aspect of ‘the life-force∞ḥaiy of the worlds’, which includes the 18∞ḥaiy blessings of prayer, and corresponding to them we perform 18 ‘shakings’ of the lulav, in six directions – three to each-and-every side, six directions that are included in the body, which is the Middle Pillar, because the lulav is called after it: ‘lo (=36) lev’ (to) him, a heart.
And there are 18 shakings, 4 times, which amount to 72, and they are: 18 shakings upon taking the lulav, 18 and 18– twice in: (Ps. 118:1) Give thanks to Y”Y – at the beginning and end of Psalm 118, 18 at (Ps. 118:25) Please Y”Y, please save! – there are 72.