As connected with objects, it is that which is to be understood, and the presiding deity there is Brahman. Three are the seats of all existent objects. A fourth is not possible.
अधिभूतं तु मन्तव्यं ब्रह्मा तत्राधिदैवतम्। त्रीणि स्थानानि भूतानां चतुर्थं नोपपद्यते॥