Mindfulness meditation is expounded most comprehensively and systematically in the Satipatthana sutta in the Majjhima Nikaya. After explaning how to establish mindfulness with 13 concrete objects (categorized into 4 areas of body, feelings, mind and dhammas), the sutta repeatedly mentions the formula regarding the insight that is to be attained by the practitioner. In this refrain, it introduces the triad of ajjhatta (internally), bahiddha (externally) and ajjhatta-bahiddha (internally and externally) necessary for the purpose of carrying out continuous observation. It is this triad that constitutes the main theme of this paper. Analayo's Satipatthana: The Direct Path to Realization (2003) is a thorough research work on this sutta, which includes traditional interpretation, works of modern scholarship, and teachings of present-day meditation teachers. I will, in this paper, summarize his treatment of this theme, "internal and external contemplation." It is Analayo's conclusion that the commentarial and Abhidhammic position to identify the "internal and external" with the "self and others" is the most appropriate and practical interpretation. Building on his philological work, I wish to introduce some information from the Mahavagga in the Vinaya about the reciprocal practice of taking care of each other: the duties of teachers and disciples, the five conditions of a patient who is difficult to take care of and the five conditions of the practitioner who is able to take care of a patient. These situations inevitably lead the practitioner to observe not only others but also oneself. In the Ambalatthikarahulovada sutta from the Majjhima Nikaya, Buddha admonishes Rahula to reflect on his actions as to whether they give pain to oneself, to others or to both. This perspective of "self, others and both" constitutes a counterpart to the triad of "internally, externally, and both internally and externally." The Buddha, further, taught Rahula to confess and reveal unwholesome bodily and oral actions that produce painful results for one's teachers and fellow practitioners of the holy path, while repelling and feeling ashamed of one's unwholesome mental actions. This suggests that bodily and oral actions are shared within interpersonal relationships while mental actions stay confined to oneself. Abhidhamma explains hiri to be the feeling of being ashamed of oneself, while otappa is the feeling of being ashamed toward someone on the outside. This suggests that there exists someone internalized deep in our psyche. In this regard, the Khandha Samyutta discusses the existence of various layers of consciousness, with or without the concept of "I," "me" and "mine." Taking all these into account, the framework of ajjhatta, bahiddha and ajjhattabahiddha functions as the observational perspective, in which a practitioner witnesses the process by which the concepts of "self' and "others" are formed.