As generally meant, Buddhist terms such as "straightforward mind" (rijucitta), "profound mind", "mind of great compassion" (mahakarunacitta) are, more or less, synonymous with bodhicittopada. Difficult to translate, bodhicittopada is not just the "thought of enlightenment" as if one could just think of it. Bodhicittotpada is the flowering (bodha) of spirit (citta). It is spirit's first manifestation (utpada) in us which is a singularly important event that makes one an authentic Bodhisattva. Fundamentally, one has not reached the level of a Bodhisattva without bodhicittotpada.
For Zen master Dogen, bodhicittopada, seemed to mean to imitate a Buddha, for example, by sitting like a Buddha. But how does a Buddha sit since the Buddha has an immaterial Dharma body? Here we must look upon imitation in the sense of resonating with Buddhahood, itself—not mere sitting. Dogen also wrote that bodhicittotpada "arises not spontaneously but only when we have a spiritual communion with the Buddha."
By and large, Zen is a propaedeutical course directed at the accomplishment of bodhicittotpada. Its literature, including its various practices such as koan instruction, constitute propaedeutical instruction.
It would be a great mistake for beginners and Buddhist clergy to patently assume that Buddhahood commences with the baptism of bodhicittotpada. Technically speaking, it is only the first stage of a Bodhisattva, despite the earth shaking experience it confers. It also needs to be addressed, that the ‘samadhi of oneness’ (ekakara samadhi) is earth shaking, too. By it one enters through the gate that separates mortal from Bodhisattva. Both the samadhi of oness and bodhicittotpada are the same.
Worth mentioning, it is easy to take spiritual awakenings (J., kensho) to be Buddhahood. But they are not. Such awakenings are akin to way stations on the road to enlightenment. Buddhahood is far different as one might imagine, and truly cosmic in its scope and power. Without going into the nuts and bolts of this subject, it is sufficient to say that Buddhahood commences with the complete exiting of the animation principle from its former condition of dependence on the temporal body which, as a mere reflection, was previously adhered to as if it were a true refuge. Thus, we come to understand that temporal existence was wrongly imbued with power while the power giver was treated as virtually non-existent! In this regard, bodhicittotpada is the first awakening of this infinite power to itself in which, for the first time, it reflects back into itself instead of reflecting into its alter and grasping the alter as itself.