The Hinayana Scriptures Implicitly Mentioning the Mental Factor of Mindfulness in the Manas

The first enlightenment factor is mindfulness. Internal mindfulness pertains to the mindfulness of the manas (mind-root), while external mindfulness pertains to the mindfulness of the consciousness. When the manas lacks the mindfulness enlightenment factor, the mindfulness enlightenment factor cannot be established, and the enlightenment factor of investigation of dharmas cannot manifest. Therefore, the manas must possess the mental factor of mindfulness. The Hinayana scriptures implicitly address the mental factor of mindfulness in the manas, let alone the Mahayana scriptures. It is only because sentient beings are burdened by heavy ignorance that they cannot comprehend the Buddhist sutras and are unable to discern this.