Part 1: Expanding Judgment causes darkness… This is obvious because Judgment (דין, din) means limitation and restraint, and by limiting the lights it causes darkness.
…by preventing the lights from radiating widely… When Judgment rules in a given light, this prevents its innate powers from expanding. …with their full force. This limitation is a lack of completeness, and when it departs, we say that the light in question becomes complete. This enables us to measure the different states of the lights from their inception until their completion – i.e. from the time the limitation has an effect until it departs altogether. (Pregnancy and immaturity are thus explained as being the outcome of Judgment – for the active influence could have conferred maturity from the outset had not the power of Judgment prevented it. All the different states of deficiency and completeness depend on the intensification or removal of restraint, and can therefore be measured according to the degree of the restraint that rules or is negated.)