Assumptions
Samanupassanā Sutta  (SN 22:47)

Near Sāvatthī. There the Blessed One said, “Monks, whatever contemplatives or brahmans who assume in various ways when assuming a self, all assume the five clinging-aggregates, or a certain one of them. Which five? There is the case where an uninstructed, run-of-the-mill person—who has no regard for noble ones, is not well-versed or disciplined in their Dhamma; who has no regard for people of integrity, is not well-versed or disciplined in their Dhamma—assumes form to be the self, or the self as possessing form, or form as in the self, or the self as in form.

“He assumes feeling to be the self, or the self as possessing feeling, or feeling as in the self, or the self as in feeling.

“He assumes perception to be the self, or the self as possessing perception, or perception as in the self, or the self as in perception.

“He assumes fabrications to be the self, or the self as possessing fabrications, or fabrications as in the self, or the self as in fabrications.

“He assumes consciousness to be the self, or the self as possessing consciousness, or consciousness as in the self, or the self as in consciousness.

“Thus, both this assumption & the understanding, ‘I am,’ occur to him. And so it is with reference to the understanding ‘I am’ that there is the appearance of the five faculties—eye, ear, nose, tongue, & body [the senses of vision, hearing, smell, taste, & touch].

“Now, there is the intellect, there are ideas [mental qualities], there is the property of ignorance. To an uninstructed run-of-the-mill person, touched by experience born of the contact of ignorance, there occur (the thoughts): ‘I am,’ ‘I am thus,’ ‘I shall be,’ ‘I shall not be,’ ‘I shall be possessed of form,’ ‘I shall be formless,’ ‘I shall be percipient [conscious],’ ‘I shall be non-percipient,’ or ‘I shall be neither percipient nor non-percipient.’

“The five faculties, monks, continue as they were. And with regard to them the well-instructed disciple of the noble ones abandons ignorance and gives rise to clear knowing. Owing to the fading of ignorance and the arising of clear knowing, (the thoughts)—‘I am,’ ‘I am this,’ ‘I shall be,’ ‘I shall not be,’ ‘I shall be possessed of form,’ ‘I shall be formless,’ ‘I shall be percipient,’ ‘I shall be non-percipient,’ and ‘I shall be neither percipient nor non-percipient’—do not occur to him.”

See also: SN 12:15; SN 12:20; AN 4:199–200; Sn 4:14