The denials of limit, magnitude, shape and composition share an argument: each describes a body as determined by a specific physical configuration, whose determination may require explanation.
A necessary existent is not dependent for its existence on an external producer or constituent parts. A composite entity that relies on its components would not fit that conception.
Distinguish our need for explanations from an entity's dependence for existence. The reasoning does not pretend to exhaustively comprehend divine reality; it excludes the type of contingent dependence associated with created bodily structures.