An excellent composite study of Bodhicitta as well as all things Bodhisattva is The Bodhisattva Doctrine in Buddhist Sanskrit Literature, by Har Dayal circa 1932. For myself it has become the bible regarding such subject matter. What I treasure most about it is that it was written before contemporary sectarian studies that always flavors said material with superficial psychophysical makeup that mars the original import of the Bodhi-structure itself. Before dining on the succulent taste of this endeavor we must first focus on those who prepare the ingredients of this marvelous meal. The Carriers of the Bodhi-seed. Bodhisattvas as well as Arhats, yes Arhats too have much ado concerning this cuisine raffinée. Recollect that one of the epithets of the Buddha is that of an Arhat, this even after his former career as a Bodhisattva.
As a spiritual-being exemplar the Arhat broke the bonds of samsara and tasted the divine fruit of liberation. In so doing the splendid realization dawned that he would never be reborn. He knew that he had accomplished what needed to be done, for he laid his burden down at the sweet feet of the Tathagatas. In so doing, he forever remained above defilements by treasuring the emancipation of the Bodhi-mind, and he cultivated all this by being zealously alone and well secluded—a total self-Meister supreme. Har Dayal provides even finer detail:
He exerted himself and strove and struggled, and thus he realized that this circle (or wheel) of Life (or the Universe), with its five constituents, is in constant flux. He rejected all the conditions of existence which are caused by the samskāras (material compounds), as their nature is such that they decay and fall away, they change and are destroyed. He abandoned all the kleças (sins, passions) and realized the state of an arhat. When he became an arhat he lost all attachment to the three worlds; gold and a clod of earth were the same to him; the sky and the palm of his hand were the same to his mind; he was like fragrant sandalwood; he had torn the egg-shell (of ignorance) by his Knowledge (i.e. as a bird is hatched); he obtained Knowledge, the abhijñās (Super-knowledges) and the pratisaṃvids (analytical Powers); he became averse to gain, avarice and honour in the world (or to existence, gain, etc.); he became worthy of being respected, honoured and saluted by the devas, including Indra and his younger brother,Viṣṇnu or Kṛṣna. (ibid, pgs. 15-16)
An Arhat carries the Bodhi-seed in that he points the way to liberation, a liberation that can only be won when one puts on the very Mind of Bodhi. In truth, an Arhat has generally gotten a bum-rap in the Mahayana—which by and large strips his significance down to just pure selfish motives with no desire to help another; the same can be said for the Pratyekabuddhas. Yet both have also helped to promulgate the Buddhadharma in one form or another. How? Some have mastered the sūtras and treatises and as such are Dharma masters. Dharma masters take the Buddhadharma as one’s own teacher and in so doing teaches others according to it, even if it’s done in an indirect manner. Sheng-yen writes in Orthodox Chinese Buddhism, “When an Arhat turns to Mahāyāna practice, he only needs to catch up with the accumulation of merit to enter the sacred stages of the bodhisattva path—his level of wisdom will not be reduced below the level of the noble stages.” Pratyekabuddhas were also given the status of special recognition:
References to stūpas for Pratyekabuddhas are found not only in the Ekottarikaāgama, however, but also in Pāli discourses. The Pratyekabuddha in fact features regularly in the early discourses in lists of those who are worthy of gifts. Such lists present Pratyekabuddhas as superior to arahants or other noble disciples, but inferior to a fully awakened Buddha. By integrating the Pratyeka-buddha, as an awakened one from the past or the distant future, into what otherwise comprises the present Buddha and his disciples, the hierarchy of gifts becomes invested with a timeless validity that applies to past, present and future times. In the absence of a living Buddha, a Pratyekabuddha then becomes the topmost recipient of gifts. Other discourses suggest that such concern with worthiness to receive gifts was a significant issue in the tradition, as they report occasions when a gift given to a former Paccekabuddha yielded abundant fruit for its giver. (Pratyekabuddhas in the Ekottarika-āgama, Anālayo)
In terms of their acquisition of bodhi, Har Dayal breaks it down into threefold fashion, three types of bodhi are cognised : çrâvaka-bodhi, pratyeka-bodhi and anuttarā samyak-sambodhi (the supreme and perfect bodhi) Of course the latter is reserved for Bodhisattvas alone.
Firstly, what of Bodhi itself? As understood by Buddhists it connotes one who knows or understands; having an attentive mind as in the Rg-veda; supreme gnosis, Enlightenment:
Bodhi or* Sambodhi, the summum bonum of a bodhisattva, is primarily and essentially equivalent to Omniscience. Of course, it has been analysed into its constituent elements,- and its various aspects have been elucidated by the Buddhist philosophers. But the simple root-idea, shorn of all accretions and amplifications, is Omniscience. D.T.Suzuki defines bodhi in terms of the dharma-kāya (cosmic spiritual Body). Ibid, pg. 19
Sattva signifies Being or True-Essence. Hence the Bodhisattva is one who has bodhi or perfect wisdom as his essence. Also, one whose essence is knowledge. It could also mean “spirit, mind, sense, consciousness.” In some circles it also translates as embryo; this particular connotation bears great import for Lankavatarians with the very advent of the Bodhi-child—or the developing Bodhisattvic seed in the Bodhi-womb. Satta in the pali does not denote an ordinary being, but “a strong or valiant man, hero or spiritual warrior.” In Tozen’s Zen School of the Unborn Mind this translates as Light Warrior. A Bodhisattva is indeed a valent Light Warrior bearing Noble Bodhi-seeds for the awakening and liberation from all dukkha.