The efficacy of mönlam or aspirations is based on the belief in the power of the mind. In Buddhism, mind has even greater power than matter in shaping our existential experience. In the most basic sense, when one wishes to do something intensely and repeatedly, such mental aspirations gradually translate into physical and verbal action, which then bring about the result. If one makes strong mönlam or mental wishes to go to Bodh Gaya, such thoughts eventually unfold into a real journey to Bodh Gaya. All good projects start with a good intention. So, it is important to make a good mönlam in Buddhism.
Then, on a more subtle level, even if our mental wishes do not directly translate into physical or verbal action, they are said to have outcomes. Buddhists believe that even purely mental actions reap results. Because our existential experience is largely a reflection of our inner thoughts and creation of our mind, when one persistently wishes and thinks about something, that thing gradually unfolds as life experience. Thus, an earnest mönlam can bring about results in the form of experience in this or future lifetimes. For example, if a person makes strong and earnest mönlam to take a certain birth and they are said to be able to take that birth through the force of their mönlam.
Based on such theory, the Buddhas and Bodhisattvas are said to have made and continue make many prayers for sentient beings. The Medicine Buddha is said to have made mönlam to cure the diseases of the world whereas Amitabha is said to have prayed to rescue from suffering anyone who hears his name. The historical Buddha Śākyamuni is said to have made mönlam to help the most unruly beings in the degenerate age. So, he is said to have come to the world in degenerate times. Because they have invested unlimited power of mönlam into such objectives, the sentient beings are said to have benefit from their mönlam. Although they have long reached fully enlightenment, their mönlam are believed to have continuous impact just as the wheels go round and round long after the person who has turned it has left. So, in order to reach Buddhahood, a person is required to make many benevolent mönlam which will later benefit the sentient beings for perpetuity.
The tradition of mönlam is also based on the belief in the flow of spiritual vibes and energies, which are not restricted by time or space. Amitabha’s mönlam are said to be effective because a devotee can receive the spiritual vibes or energies of his mönlam and connect to him spiritually, even when a person lives in a different world and era.