Yoga Sutras of Patanjali 2.19

2.19

viśeṣāviśeṣaliṅgamātrāliṅgāni guṇaparvāṇi ||

The grades or layers of the Three Potencies are the defined, the undefined, that with distinctive mark, that without distinctive mark.

Or, as we might say, there are two strata of the physical, and two strata of the psychical realms. In each, there is the side of form, and the side of force. The form side of the physical is here called the defined. The force side of the physical is the undefined, that which has no boundaries. So in the psychical; there is the form side; that with distinctive marks, such as the characteristic features of mind-images; and there is the force side, without distinctive marks, such as the forces of desire or fear, which may flow now to this mind-image, now to that.