Mastering in something. A part of you that may be boxing yourself into a life situation. Self-containment, being conservative or being stuck in the ego. Your higher self is merging sections of you together, such as the heavenly you and the earthly you or the spiritual and material parts of you. The rectangle is a sign to dig deep within, to examine your beliefs, patterns, programs, attitudes, emotions, judgements, limitations and thought processes.
See Box, Shapes, Integrate.