“On considering these instances it is indubitably clear that sati has a crucial role to fulfill in the realm of samatha. This might be why the Cūḷavedalla Sutta speaks of satipaṭṭhāna as the "cause" of concentration (samādhinimitta)....

On the other hand, however, to consider satipaṭṭhāna purely as a concentration exercise goes too far and misses the important difference between what can become a basis for the development of concentration and what belongs to the realm of calmness meditation proper. In fact, the characteristic functions of sati and concentration (samādhi) are quite distinct. While concentration corresponds to an enhancement of the selective function of the mind, by way of restricting the breadth of attention, sati on its own represents an enhancement of the recollective function, by way of expanding the breadth of attention. These two modes of mental functioning correspond to two different cortical control mechanisms in the brain. This difference, however, does not imply that the two are incompatible, since during absorption attainment both are present. But during absorption sati becomes mainly presence of the mind, when it to some extent loses its natural breadth owing to the strong focusing power of concentration.”