The unabridged Hanyu Da Cidian ("Comprehensive Chinese Word Dictionary"), which is lexicographically comparable to the Oxford English Dictionary, defines shengtai with two meanings: There is no standard English translation for Chinese shengtai and scholars have rendered it as: "Autogestation" is Christine Mollier's unique translation, "the generation of an embryo of immortality, the germ of a perfect being, develops within the practitioner's body through a process of 'autogestation' that can be labelled as an internal sexual alchemy" (2016: 87).

Many Indian Buddhist scriptures portrayed the female body, especially the womb, as impure, and characterized fetal gestation as the "focal point of human suffering", representing the cosmic misery of saṃsāra ("cyclical birth and death").

His mother Queen Māyā supposedly was impregnated while dreaming that a white elephant entered her body, her pregnancy was painless, and the Buddha was born from underneath her right arm.

These narrative elements helped establish the Buddha not only as different from ordinary people but more specifically as "impervious to the pollution and suffering understood to ordinarily accompany sexual intercourse, fetal gestation, and birth" (Buckelew 2018: 376).

According to the Humane King Sutra, "In these [first ten minds], the bodhisattva is capable of transforming sentient beings in small measure and has already surpassed all of the good stages of the [lesser] two vehicles.

On the one hand, a "soteriology of sudden liberative vision" was associated with the words rulaizang "embryo of the thus-come one" or foxing "buddha-nature", typically used with the Chinese verbs guan (觀, "to view; look at; watch") or jian (見, "to see; to appear").

Medieval Chinese Buddhist texts did not mention "seeing" the shengtai, but rather used the verbs ru (入, "to enter"), tuo (託/托, "to conceive"), chu (出, "to be born from"), and most commonly yang or zhangyang (養 or 長養, "to nurture").

The 594 Mohe Zhiguan (摩訶止觀, Great [Manual of] Calming and Contemplation) Buddhist doctrinal summa, based on lectures given by Zhiyi (538–597), the fourth patriarch of Tiantai Buddhism, discusses shengtai ("embryo / womb of sagehood") meditation in terms of the sanfa (三法, "three kinds of dharma": precepts, concentration, and wisdom).

Zhiyi also uses shengtai to explain busheng sheng (不生生, "nonbirth-birth") that the Mahāyāna Mahāparinirvāṇa Sūtra describes as "peacefully abiding in worldly truth, when someone first emerges from the womb, this is called 'nonbirth-birth'."

The 952 Zutang ji (祖堂集, Anthology of the Patriarchal Hall) version mentions zhangyang shengtai (長養聖胎, "Nurturing the Sacred Embryo"): What the heart/mind produces is called form.

Zongmi also mentions "feeding the soul and making the sagely embryo grow [養神聖胎增長]" in his Chanyuan zhu quan ji duxu (禪源諸全集都序, Preface to a Collection of Texts on the Origins of Chan") (Despeux 2016: 152).

Gufeng Zongmi notes the figurative resemblance between the embryo of sagehood and the impregnation of the storehouse consciousness—the eighth of the Eight Consciousnesses in the Yogācāra philosophical tradition, which is said to store the impressions (vāsanāḥ) of previous experiences, which form the seeds (bīja) of future karma in this life and in subsequent rebirths.

When by means of but a single thought one awakens to this perfect and wondrous mind, the storehouse consciousness (ālāyavijñāna) is thereupon impregnated with the seed of sagehood [熏成聖種], though conditions have not yet brought it to external manifestation; thus, it is like the beginning of pregnancy.

By the tenth century, it became increasingly common for Chan monks to be described as recluses nurturing the embryo of sagehood in isolated forests or on mountains.

Subsequently, it became a literary trope that after a Chan monk's enlightenment was certified through lineage transmission, they would nurture the embryo of sagehood during a period of reclusion or aimless wandering before returning to public life (Buckelew 2018: 397).

In distinction to Buddhism emphasizing the spiritual or psychological dimensions of an adept's experience, Daoism focuses upon corporeal metaphors for the physical or psychophysiological sensations such as inner breathing, inner flows, and inner heat (Despeux 2016: 153).

The circa mid-second century CE Zhouyi cantong qi (Token for the Agreement of the Three According to the Book of Changes), a fundamental treatise on Inner Alchemy, poetically describes the birth of a spiritual embryo, which is usually connected with its transcendence of the mortal body.

Already in the second and third centuries, some Daoist writings referred to religious practices of peitai (培胎, "fostering the embryo") or of nurturing an infant god, called the chizi (赤子, "red child"), that resides inside the body.

The Shangqing School scriptures, believed to have been revealed to Yang Xi in the late fourth-century, developed these practices into formalized and complex meditative procedures for visualizing one's own spiritual rebirth (Buckelew 2018: 402).

The fourth or fifth century Huangting neijing yujing zhu (黃庭內景經註, Commentary to the Scripture on the Inner Effulgences of the Yellow Court) has one of the earliest references to an allegorical embryo, "the embryo-immortal [胎仙] dances to the three couplets of the heart-lute."

The circa ninth-century Zhen longhu jiuxian jing (真龍虎九仙經, Scripture of the Nine Transcendents and the Perfected Dragon and Tiger), which contains commentaries attributed to Ye Fashan (616–720) and Luo Gongyuan (羅公遠, 618-758), instructs an adept to "imagine the true essence of the two kidneys merging into a single qi and the blood of the heart descending to combine [with it], whereupon the image of the infant is formed."

The Ye commentary explains that the embryo of an immortal body is formed by visualizing the same jing (精, "semen") and xue (血, "blood") substances whose combination in sexual intercourse was understood to cause normal pregnancy.

By combining them within oneself according to the proper timing and procedures, one "appropriates the efficacy of sexual intercourse between husband and wife, so that the embryo of sagehood is completed and true qi is born."

Zhang Boduan (987-1082), one of the most famous Inner Alchemists of the Song period, was the first to use the expression shengtai ("sagely embryo") in the context of Internal Alchemy, and the first to have explicitly referred to a symbolic pregnancy process (Despeux 2016: 149).

Zhang's advocacy of xingming shuangxiu (性命雙修, "dual cultivation of nature and lifespan") implies the inadequacy of any Buddhist practice that focuses exclusively on witnessing buddha-nature.

twelfth century) describes egressing his spirit through the fontanel: "I have put into practice the work of old for a full year, and the six vessels have already stopped, the breath has returned to its root, and in the [lower] Cinnabar Field there is an infant (ying'er).

Then comes the climax of the entire process: "As this infant grows, [there comes a point when it] cannot reside in this cavity [of the lower Cinnabar Field] any longer; so a fissure and then an orifice naturally appear, and it emerges through the top of the head.

For instance, the 1615 Xingming guizhi (Principles of Balanced Cultivation of Inner Nature and Vital Force, the source of several illustrations above) uses fashen (法身, "Body of the Law; dharmakāya") as a synonym for shengtai.

The Chinese Buddhist concept of the shengtai "embryo of sagehood" originated in medieval China as a trope describing the complex bodhisattva path invented in the apocryphal Humane King Sutra.

In Chan Buddhism, nurturing the embryo of sagehood became a metaphor for a liminal period of idealized mountain and forest reclusion undertaken by enlightened masters who were still awaiting appointment to an abbacy.