The Arhat possesses the four fully developed mentality of loving-kindness (mettā), compassion (karuṇā), empathetic joy (muditā), and equanimity (upekkhā)—collectively known as the “Four Immeasurables.” However, despite their perfection, these Four Immeasurables still cannot compare to the Bodhicitta of a Bodhisattva. This may prompt some to wonder: What exactly does “immeasurable” mean? Why, even though they are already called “immeasurable minds,” can they not qualify as Bodhicitta? Below are explanations for these two questions.
The First Question: What Are the Four Immeasurables?
“Loving-kindness means maintaining a gentle, affectionate attitude toward all beings as though they were one’s own relatives. Compassion, also called ‘uprooting suffering’, refers to the wish to free all beings from pain, thus also called “uprooting suffering”. Joy, or meditative bliss, is a peaceful and uplifted mental state. Equanimity is the relinquishment of self-centered views—the abandonment of the notions of ‘self,’ ‘mine,’ and self-grasping.
Also translated as the ‘Four Brahmavihāras’ or the ‘Four Sublime States,’ they originated in ancient Indian Brahmanism and were later adopted by Buddhism. Practitioners are required to extend these four attitudes to boundless limits; hence the name ‘Four Immeasurable Attitudes’ or ‘Four Immeasurable Contemplations .’” (Wikipedia)
The Dictionary of Buddhist Studies states: “These four states of mind are radiated universally toward immeasurable sentient beings, and give rise to immeasurable merit; therefore, they are called the ‘Immeasurable States of Mind.’”
In the foregoing explanation, the key term here is “immeasurable.” What, then, does “immeasurable” exactly mean? On the surface, it means “boundless” or “infinite,” but more deeply, how can a person’s mind actually be “immeasurable”?
First, the so-called “gauge” (pramāṇa) is defined in Buddhist logic (pramāṇavāda), especially by Dignāga and Dharmakīrti, as “ freshly non-fraudulent cognition”—in simple terms, a reliable source of knowledge. In a narrow sense, it refers to “the criteria or basis for knowing an object ”; in a broader sense, it encompasses “the methods, processes, and results of cognition, as well as the standard for determining truth or falsity of knowledge.” Cognition that is fallacious is called “non-valid cognition.”
More simply, “gauge” refers to the “cognitive faculty” and the “cognitive method” that are unique to sentient beings. Cognitive faculty refers to a general term, including the six sense faculties through which we apprehend both the world and ourselves: cognition through the first five senses is termed direct cognition (pratyakṣa), while the logical inference of the mind faculty is termed inferential cognition (anumāna). And what about cognitive methods? This refers to the various tools and procedures we employ in apprehending the world in order to arrive at a conclusion. For example, to measure the height of a mountain, one may use a laser rangefinder or a barometric altimeter as the instrument; one may measure the distance section by section or in one go as the procedure; and the result is the height of the mountain in meters. If this conclusion is correct, then according to the principles of Buddhist logic (pramāṇavāda), it is considered a valid cognition (pramāṇa); if it is incorrect, then it is classified as non-valid cognition (apramāṇa).
But how can one “gauge” the formless and intangible mind? Naturally, the mind cannot be measured by the five senses, and ordinary beings cannot accurately measure their own and other’s minds even with mental faculty . Thus, the only way to precisely measure the mind is by “observing the mind by mind.” Yet, if one observes the mind in this way, how can it be considered truly “immeasurable”?
Since “pramāṇa” refers to a mode of cognition, cognition itself can be divided into the cognizer (the subject that apprehends) and the cognized (the object apprehended). Since the Four Immeasurables—loving-kindness, compassion, empathetic joy, and equanimity—constitute the four attitudes as objects perceived, an Arhat can, when “observing the mind with the mind”, naturally apprehend them. Therefore, the mind, as the perceiving subject cannot be said to be truly “immeasurable.”
But what about the “cognized”? Having fully realized the truth of “no-self of persons” and being completely free from any trace of grasping at self, an Arhat is able to apply loving-kindness, compassion, joy, and equanimity toward all sentient beings. Because the number of sentient beings perceived is truly boundless, objects of cognition can indeed be considered “immeasurable.”
We now moving forward to the second question: if Arhats can apply the Four Immeasurables to all beings, why is this still fundamentally different from the bodhicitta of a Bodhisattva? Do Bodhisattvas not likewise engage with all beings through loving-kindness, compassion, joy, and equanimity?
Not exactly. The Four Immeasurables of an Arhat differ essentially from the Bodhicitta of a Bodhisattva in both depth and scope.
The mind of sentient beings can be broadly divided into two categories: the ordinary and the noble. The fundamental difference between the two lies in whether the mind still clings to the notion of a personal self. In Yogācāra (Consciousness-Only School), the consciousness of sentient beings persistently attaching to a personal self, is referred to as manas (the Seventh Consciousness). The underlying continuum of consciousness bound and conditioned by the manas, is called the ālaya-vijñāna (foundation or storehouse consciousness). In plain language, whether one call it “manas” or “grasping at a self” , it is simply the innate sense of individuality that ordinary beings are born with.
To become an Arhat signifies having realized the emptiness of “self,” accompanied by the elimination of the attachment to self. From the Yogācāra perspective, this corresponds to the extinction of manas, which in turn causes ālaya-vijñāna to lose its self-centered mode of cognition. Simply put, this implies that the sense of individuality of ordinary beings ceases to exist. Such a mind free from individuality ought, by its very nature, to unrestrainedly and ceaselessly benefiting immeasurable and boundless beings. However, Arhats do not act this way; they typically enter nirvāṇa (extinguishment), a meditative absorption in which perception and sensation cease, and thereby cutting them off from external world, known as nirodha-samāpatti (cessation absorption).
Why is this case? It is simply because Arhats do not possess Bodhicitta.
The mind of a Bodhisattva is known as Bodhicitta, which can be devided into two types: Conventional Bodhicitta and Ultimate Bodhicitta. Conventional Bodhicitta, in conceptual terms, is a strong aspiration to attain Buddhahood for the specific purpose of liberating all sentient beings. Ultimate Bodhicitta, as described in Mahāyāna Buddhism, is the very nature of all phenomena: emptiness (śūnyatā).
As for Conventional Bodhicitta, this state of inner consciousness can be observed and measured. When a practitioner cultivates such mental state to a firm and stable level, they enter the first of the Fivefold Path (pañcamārga) of Mahāyāna Buddhism—the Path of Accumulation (pañcamārga). Thus, such mental state of conventional Bodhicitta, from the standpoint of the subject of cognition—the perceiving consciousness, can indeed be measured. Yet, regarding the object apprehended, namely the perceived attitude—based on the aspiration “to attain Buddhahood for the liberation of all sentient beings”—can be divided into two aspects: first, to liberate all sentient beings, and second, to attain Buddhahood. The first, liberating all beings, may rightly be called “immeasurable.” As for attaining Buddhahood, this pertains to the Bodhisattva’s ultimate bodhicitta.
Ultimate Bodhicitta—emptiness, as the ultimate goal of the Bodhisattva’s practice, is profoundly different from the Arhat’s realization of selflessness. A Bodhisattva not only realizes “Selflessness of persons” but also “Selflessness of phenomena”—the complete absence of dualistic distinctions in cognation. In such absolute wisdom, the mind knowing itself directly, deviod of any notion of perceiving subject and perceived object in duality, It is truly beyond conceptual fabrications —a genuinely inconceivable “immeasurable.” Therefore, it is unlike the Four Immeasurables or conventional bodhicitta, whose ‘immeasurability’ merely refers to different levels of dichotomizing orientation of consciousness.
Attaining Buddhahood, in Yogācāra terms, means the transformation of the manas into the Wisdom of Equality (samatājñāna), and the ālaya-vijñāna into the Great Mirror-Like Wisdom (ādarśajñāna). Not only is the sense of individuality completely gone, but one also realizes that all sentient beings share the same nature as one’s own mind—an indivisible emptiness. From this realization, one naturally generates “great compassion rooted in non-duality” (mahākaruṇā)—unstinting loving-kindness toward all beings, embodied by the mind of awakening , in which no independent beings actually exist, and does not passively enter an extinguished state of release (nirvāṇa), isolated from other beings. Instead, one selflessly, fearlessly and boundlessly benefits all beings.
As for the Arhat, since the Four Immeasurables are not equivalent to the Bodhisattva’s conventional bodhicitta, Arhats lack the intense aspiration and clear vision to lead all beings to Buddhahood. Therefore, they are unable to realize emptiness in the Mahāyāna sense. Although the manas of an Arhat is extinguished, it cannot be transformed into the Wisdom of Equality; and although the ālaya-vijñāna loses its self-centeredness, it cannot be transformed into the Great Mirror-like Wisdom. Consequently, the Arhat cannot clearly and thoroughly apprehend the essential nature and the laws of dependent origination of immeasurable beings and other dependent phenomena. They thus fall into the absorption of cessation (nirodha-samāpatti), and naturally their so-called “nirvāṇa” stands in dualistic opposition to saṃsāra. As a result, they are unable to benefit sentient beings in a truly immeasurable and boundless way.
From this, it becomes clear that the Arhat’s Four Immeasurables, which merely serving as the foundation for the cultivation of Bodhicitta, differ greatly from Bodhisattva’s bodhicitta. Although such practice of Arhats bears the epithet of “immeasurable,” its falls far short in both depth and scope when compared to that of a Bodhisattva. Consequently, this distinction allows us to clearly apprehend why Bodhicitta constitutes the fundamental criterion that differentiates Mahāyāna from Hīnayāna Buddhism.
May all Mahāyāna practitioners give rise to authentic and perfect bodhicitta!
