The Three Pillars
The left side of the Tree of Life (which includes Binah, Geburah, and Hod) is known as the Pillar of Severity. This side tends towards discipline, control, and dominance.
The right side is known as the Pillar of Mercy (and contains Chokmah, Chesed, and Netzach.) This side tends towards mercy, compassion, and “letting things be.” The left and right pillars are also known by their Hebrew names Boaz and Jachin (both of which originally stood in King Solomon’s Temple, the first Temple in Jerusalem.)
The center pillar (which includes Kether, Tiphareth, Yesod, and Malkuth) is the “Pillar of Mildness.” The center pillar, also known as the Pillar of Equilibrium, tends towards harmony, balance, and unity.
A popular axiom of the Golden Dawn is “Unbalanced Mercy is weakness and the fading out of the Will. Unbalanced Severity is cruelty and the barrenness of Mind.”
The Tree of Life is about balancing this tension of opposites. Traditionally, the Pillar of Mercy corresponds to the left side of your body, while the Pillar of Severity corresponds to the right side of your body. I imagine my clenched right fist as Geburah, a good symbol for the entire Pillar of Severity. My open left hand is the mercy of Chesed. With myself in the center, I make wise and balanced decisions. This is the essence of practical magick.