Four Phases
Days in a season when the Five Elements are in the 'Phase' (secondary prosperity) state, traditionally considered auspicious for construction, planting, and seeking offspring.
The 'Four Phases' refer to days within each season when the Five Elements are in the 'Phase' (or secondary prosperity, with momentum second only to the season's dominant element) state. For example, in spring when Wood is prosperous, Fire is in the 'Phase' position. Traditionally, it was believed that on these days, the power of the related element is relatively abundant and stable. Therefore, old almanacs often recommended them for activities like construction and earth-moving, planting vegetation, or praying for children, to harness the season's prosperous energy.