In general, either the specific term or the compound term may be applied to this term, mind itself [sems nyid, cittā ].
In the first case [the specific term], the mind [sems, citta] and all mental factors [sems las byung, caitta], the cause of samsara, are concepts which reify the three realms. The Satyadvayavibhaṅga states:
The mind and mental factors which possess the aspect
of the reification of the three realms are concepts.
The Precious Introduction of Buddhahood Secret Tantra states:
Listen, Guhyapati, the mind and all mental factors are phenomena of samsara!
Therefore, since the actual nature of the concepts of mind and mental factors makes one wearied [dub] and fatigued [ngal] again and again in samsara, now, nonconceptual wisdom, the dharmadhātu, the prajñāparamita which pacifies all proliferation, is a resting place in which one can relax.
In the second case [the compound term], the assembly of concepts that have engaged for a long while in deluded appearances of the mind and are wearied by samsara are placed without fabrication in the state of the pacification of proliferation, a resting place for relaxing in the nature of the mind. This is similar to tired [thang chad] and wearied travelers resting their bodies, voices and minds after collapsing in a resting place and relaxing.
From the perspective of ease in understanding, when the specific term, “mind itself” [sems nyid], is used, it is the mind and all mental factors. “Relaxing” shows freedom from proliferation as the self-originated wisdom. When the compound term, the “nature of mind” [sems nyid] is used, it is naturally luminous and “relaxing” demonstrates the pacification of conceptual engagement.
Further, if it is asked, “What is the mind?,” [the mind] cannot persist for an instant or a single moment of time. If one tries grasp it, it cannot be held. If one tries suppress it, it cannot be pushed down. If one tries to bind it, it cannot be tied. It can wander in an instant, racing throughout all the world, mountains, valleys, India, China and so on. This is called “the mind.” This is the same mind that ascends to the stage of buddhahood and this is the same mind that descends into Avici Hell. Since the foundation of samsara and nirvana is encountered in this same mind and also, the foundation of all virtuous and nonvirtuous concepts is this same mind, it is called the “mind itself.”
Relaxation [ngal gso]:
“Fatigue” means tired, fatigued or wearied. In what way? This mind has wandered here on the great plain of samsara’s three realms without any beginning. Having been born in Avici hell, it is fatigued by the burden of the affliction of anger. Having been born as an animal, it is fatigued by the burden of ignorance. Having been born as a ghost, it is fatigued and wearied by the burden of desire.
The example is a vast plain of sand without any boundary in an unknown place, a blazing pit of intense heat in which not even the name “moisture” and “cool shade” exist. No matter what direction one looks, one cannot estimate its size, like the boundary of space. One is alone, without a path or companions. The body is fatigued, weighed down with a very heavy burden. When traveling, the sun above oppresses and torments the body with hot rays of sunlight; below, the intense heat of the sand burns the body. Since there is suffering in the mind, one is depressed and fearful. When the loud sound of the breath of the one wearied by unbearable hardships seems to fill the universe, a person needs to relax after dropping their burden. In the same way, each of our minds has wandered in the place of limitless samsara oppressed by the burden of the three or five poisonous afflictions and has become fatigued.
If it is asked, “How can it relax?,” temporarily, it can relax on the stage of gods and humans; thereafter, it can relax on the stage of śrāvakas and pratyekabuddhas; then it can relax it on the stage of the perfect buddhahood of the bodhisattvas; ultimately, it can relax on the stage of the result of unsurpassed perfect buddhahood. Since this text, Relaxing in the Nature of Mind, is a comprehensive clear explanation of the unmistaken method for that, the text is also given that name.