The Tree of Life diagram may be viewed in a number of ways. One of these is the idea of three ‘columns’ or ‘pillars.’ These are often called the column of “Mercy” on the right and “Judgment” on the left. The column in the middle is seen as the “balance” between the two.
Mercy and Judgment are very precise terms, and in fact apply to a specific Sefirah on each side (Chesed on the right and Gevurah on the left). It’s easier to grasp things if we think more in general terms of the right being; proactive and expansion (force) and the left being; reactive and constriction (form).
These concepts apply in the ‘physical’ and spiritual worlds, only differently depending on what they are dealing with. (In our lives we deal with physical circumstances, emotion and intellectual matters. In the spiritual words there are principles, forces, entities, etc.) For instance, we might consider ‘restriction’ in our physical life as being on a low-carb diet, whereas strictness in the spiritual worlds may have to do with prayer and fasting, where superfluous thoughts are blocked out so we can focus on what matters.
The columns, as with the Sefirot themselves, are not ‘good’ or ‘bad.’ Thus things that ‘restrict’ the light of G-d emanate emanate from the left side, as does Torah which instructs on the negative commandments – the things we should not do.
