The eight century philosopher Maṇḍana tried to streamline the distinction among various types of sacrifices he inherited from the Mīmāṃsā school. The Mīmāṃsā distinguishes between:

• fixed sacrifices one has to perform throughout one’s life
• occasional sacrifices one performs when the occasion arises (e.g., the birth of a son)
• elective sacrifices one performs in order to obtain a coveted result

It is also noteworthy that the auxiliary acts of fixed and occasional sacrifices can be performed “as much as one can”, whereas auxiliaries of elective sacrifices need to be performed exactly as prescribed.
The motivator of the former two groups seems to be the fact that the Veda prescribes them, whereas the motivator of the latter group seems to be the fact that one desires their result. But this is weird, given that they are enjoined by prescriptions which have a comparable form. Maṇḍana tried to find a way to have the same motivator for all. This is how he develops his argument:

1. Prima facie view: The motivator can only be the fact that one desires a given result. In the case of fixed sacrifices, the result needs to be something one desires fixedly, like happiness.
2. This hypothesis does not stand to reason, because the following three aspects of fixed sacrifices remain irreconcilable, namely their being fixed, their having a result and the fact that their auxiliaries needs only to be performed as much as possible. In fact, if they need to have a result, they cannot be fixed, since one would cease performing them as soon as one’s desire for them were appeased.
3. Hence, the desire for the result can be the motivator for the actively undertaking of sacrifices, whereas the fear for a sanction needs to be the motivator for the not-ceasing to perform them.
4. Final view: No, the above contradiction can be avoided because the fixedness is not just something one arrives at pragmatically, due to the fact that one happens to desire happiness all the time. Rather, their fixedness is prescribed in the Veda, hence it is surely not the case that it ceases. Consequently, one just needs to correctly identify a desire which never ceases, and this is the desire to eliminate accumulated bad karman. People who are currently suffering will be keen in eliminating bad karman in order to eliminate the cause of their sufferings. And people who want to achieve new goals will also want to eliminate bad karman, since they know that this could hinder them.
5. Thus, it is true that all sacrifices are motivated by desire. The desire motivating fixed sacrifices never ceases and needs to be identified as the destruction of bad karman, because its fixed nature is itself prescribed by the Veda.

As often the case, the pars destruens is almost more interesting than the pars construens.