The Receptacle as an Emanation of a Buddha
The entity invited to the receptacle is seen as one of the Form Bodies of a buddha. The following verse from the Rab tu gnas pa mdor bsdus pa'i rgyud ("Consecration Tantra"; RNDG) is recited in almost every consecration.
As all the buddhas, from [their] abodes in Tuṣita heaven, entered the womb of Queen Māyā, likewise may you enter11 this reflected image (gzugs brnyan). (RNDG sDe dge: 293-294)
A buddha is invited to abide in a receptacle in a manner reflecting the periodic birth of an Emanation Body (nirmāṇakāya, sprul sku) of the buddhas in the samsaric world according to the Mahāyāna conception. (This verse alludes also to the notion that a new receptacle is not created but "born.") Similarly, in the consecration work by Brag phug dGe bshes (b. 1926) the ritual master requests:
May these receptacles consecrated by me, the vajra holder, having become receptacles of worship and loci of prostration for all beings, actually perform the actions of the Emanation Body of a buddha. (299-300)
Guru bKra shis distinguishes three types of Emanation Bodies.
The supreme Emanation Bodies (mchog gi sprul sku) are those appearing in the world in the manner of the twelve deeds [of the Buddha]. The born Emanation Bodies (skye ba sprul sku) are those appearing as sentient beings in the manner of āryas, ordinary people, etc. Made Emanation Bodies (bzo sprul sku) are those appearing in an unanimated manner, such as stūpas, boats and bridges. (vol. 1: 128-129)[page 295]
Here stūpas are classified as Emanation Bodies of the buddhas. Likewise most of the residents around Bodhanath Stūpa in Nepal consider that stūpa as a reincarnation. As an emanation of a buddha in its Form Bodies the receptacle acts for the sake of sentient beings. It "looks with a compassionate eye on the trainee (gdul bya) until the end of saṃsāra" (Gung thang: 102). It will create faith and devotion in those who see it and induce them to generate the mind of enlightenment (bodhicitta, byang chub sems) (RNDG sDe dge: 294). The presence of an emanation will be a source of blessing (adhiṣṭhana, byin rlab) for that locality, a cause of auspicious events (maṅgala, bkra shis) (rMor chen Kun dga' lhun grub: 537). As an emanation the receptacle not only acts for the sake of beings but also serves as a base for the accumulation of merit.
As long as a king has not appeared in the capital, he does not possess any political power. Similarly, as long as the consecration is not completed, [the receptacle] is unworthy of worship.12
In sum, a receptacle serves to localize a certain emanation of one of the buddhas and bodhisattvas currently present in the world according to the Mahāyāna, thereby making them available for interaction with human beings.13 It supplies a rather metaphysical Mahāyāna idea with a concrete sense.