The second foundation of mindfulness discriminates between feelings of the flesh and feelings not of the flesh, but there is a skill development in the Anapanasati sutta which precedes that. The area of development of pleasurable feeling not of the flesh is crucial to the practice as mind as a conditioned phenomenon will starve without recourse to pleasant feeling. The following sutta is delivered to a layperson who is in the same position as many western Buddhists and therefore is appropriate to them, as contrasted with the suttas delivered to monks and focusing on the arahant level, which are not appropriate. Suttas should not be read indiscriminately:
"Even though a disciple of the noble ones has clearly seen as it actually is with right discernment that sensuality is of much stress, much despair, & greater drawbacks, still — if he has not attained a rapture & pleasure apart from sensuality, apart from unskillful mental qualities, or something more peaceful than that[4] — he can be tempted by sensuality. But when he has clearly seen as it actually is with right discernment that sensuality is of much stress, much despair, & greater drawbacks, and he has attained a rapture & pleasure apart from sensuality, apart from unskillful mental qualities, or something more peaceful than that, he cannot be tempted by sensuality.”—-MN 14
Being designed for beginners the Anapanasati sutta is also appropriate for laypeople and the importance of development of pleasant feelings not of the flesh is shown in the second terrad which focuses on their development:
"[5] He trains himself, ‘I will breathe in sensitive to rapture.’ He trains himself, ‘I will breathe out sensitive to rapture.’ [6] He trains himself, ‘I will breathe in sensitive to pleasure.’ He trains himself, ‘I will breathe out sensitive to pleasure.’ [7] He trains himself, ‘I will breathe in sensitive to mental fabrication.’[4] He trains himself, ‘I will breathe out sensitive to mental fabrication.’ [8] He trains himself, ‘I will breathe in calming mental fabrication.’ He trains himself, 'I will breathe out calming mental fabrication.’—-MN 118
This does not mean hours of boring focus on the breath. It begins with the first tetrad where the central part of the tetrad gives attention to the body in an investigation of the energies coursing through as a basis for locating pleasurable feeling. After that energy-intensive process the body is calmed. This is a microcosm of the process of the seven factors of awakening, which are divided into two groups of active and passive factors (SN 46.53):
“[3] He trains himself, ‘I will breathe in sensitive to the entire body.’[2] He trains himself, ‘I will breathe out sensitive to the entire body.’ [4] He trains himself, ‘I will breathe in calming bodily fabrication.’[3] He trains himself, 'I will breathe out calming bodily fabrication.’—MN 118 section A
Note the instruction to “train.” This means pleasurable feeling does not arise spontaneously in a strong form, but must be practised like a physical exercise. The second tetrad then goes on to train that development in preparation for the second foundation of mindfulness, and to fulfil the necessary condition of MN 14. Pleasurable feelings not of the flesh are formally referred to as “jhana,” but that includes any pleasurable feeling in the approach to jhana, the brahma-vihara “joy in the success of others,” and the sense of joy in the dhamma described in AN 11.12:
“gains joy connected with the Dhamma. In one who is joyful, rapture arises. In one who is rapturous, the body grows calm.”
All the sources of pleasurable feeling must be discriminated in quality as opposed to feelings of the flesh and in the beginning arise in the body.