The Śūraṅgama Sūtra, Volume 10: The Delusive Constructions of the Five Aggregates

Original text: 汝体先因。父母想生。汝心非想。则不能来。想中传命。如我先言。心想醋味。口中涎生。心想登高。足心酸起。悬崖不有。醋物未来。汝体必非。虚妄通伦。口水如何。因谈醋出。是故当知。汝现色身。名为坚固。第一妄想。

Explanation: Your material body first came into being because of the thought of your parents. If your mind had not thought, you would not have been drawn to your parents, and you would not have come to transmit your life within their desire-thought. In the neutrino-body (antarā-bhava), because the manas of sentient beings longs for conception and longs for a material body, they encounter their parents and enter the womb. As I said before, if the mind thinks of the sour taste of vinegar, saliva arises in the mouth; if the mind thinks of climbing a high mountain, a sour, aching sensation arises in the soles of the feet. There is no cliff actually present before you, nor has any sour object appeared in front of you, and your body certainly has not come into contact with the objects you imagined—so why does saliva flow out from talking about the sour taste of vinegar? Therefore you should know that the material body that appears in you is called the first delusion, the delusion of solidity. This means that the aggregate of form (rūpa) is the delusion of solidity.