Śūraṅgama Sūtra: An Epitome of the Buddha's Teachings on the Tathāgatagarbha 

This sūtra (an epitome-translation based on the relevant section in "Buddha-Dharma" by BDK) involves a discourse between the Buddha and Ananda, a prominent disciple, exploring profound philosophical and spiritual questions about the nature of the mind and awakening.
Ananda questions his understanding of the mind's location and its function, prompted by his initial inability to overcome the allure of a maiden (in last week's video), which demonstrated his spiritual deficiencies. The Buddha uses various analogies and questions to help Ananda and others present to transcend conventional perceptions of the mind and recognize its true nature. This discussion extends to other disciples and figures, like King Prasenajit, who share their insights and learn from the Buddha's teachings about the impermanence of the physical world and the eternal nature of the original mind, or Tathāgatagarbha. The teachings emphasize the non-duality and inherent purity of the original mind, unswayed by external conditions, which is a central concept in Mahayana Buddhism's philosophy of inherent Buddhahood. The dialogue culminates in a deeper understanding among the disciples, leading to a collective aspiration to achieve awakening and benefit all sentient beings, reflective of the Mahayana ideal of the bodhisattva.