The mandala is an intricate and complex circular diagram that denotes a sacred location and usually has a central deity and four directions; it is an imaginary palace contemplated in vajrayana practices. The diagrams are sometimes elaborately executed with grains of colored sand and are used for empowerments and elaborate meditation practices. The mandala offering, the third of the four special foundations, perfects the accumulation of merit by repeatedly offering the entire universe to the sources of refuge.