The question of what meditation does, or even what it is, is a challenging one to answer, since the label of “meditation” covers such a diverse, wide-ranging set of techniques and practices.
As a first approximation, we might say that meditation is a practice that trains or habituates the mind to operate, and/or to perceive the world, in some specific way. This in turn will have predictable consequences for how the regular meditator will respond to the world in everyday behavior and action.
Meditation and the Threefold Division of Philosophy
This initial account reflects the basic division of philosophy into what the Greeks called logic, physics, and ethics (and also reflects a corresponding division used by Sanskrit-speaking philosophers in India).
At the level of basic functioning, meditation trains the mind to take in (or to filter out) data from the world, and to follow certain chains of association or patterns of cognitive motion from one idea, or one bit of data, to another. All of this belongs to the suite of cognitive and epistemic processes that the Hellenistic philosophers called “logic,” and which Sanskrit-speaking philosophers callpramāṇavāda, “the study of the instruments (or means) of knowing.”
Meditative disciplines, whether implicitly or explicitly, also serve to reinforce or to undercut certain accounts or pictures of the world—whether that is the wide outer world, or what we might call our inner world, or our sense of self. All of this falls squarely into the Hellenistic category of “physics,” the broad study of external and human nature. In Sanskrit-language philosophy, this is the domain of prameyavāda, “the study of the objects of knowledge.”
Finally, the consequences of these shifts in worldview and cognitive process will fit neatly into the Hellenistic notion of ethics: the ways that we respond, in thought, word, and deed, to both the outer world and our inner/mental world.
And of course, different sorts of meditative practices will have predictably different results, at all three levels of logic, physics, and ethics.
A few examples might help to show some of the wide range of different results that come from different meditative techniques.
With the practice of lectio divina, the meditator develops the habit of noting connections between the problems and circumstances of his/her own life, and ideas and systems of meaning that come from outside him/herself. This in turn tends toward a greater openness and responsiveness to serendipity and synchronicity, a sense of deeper currents of meaning in the cosmos.
Discursive meditation helps the meditator to develop a single-pointed focus, able to bring unwavering attention to any problem, question, or idea at will. It also develops his/her capacity of probing analysis of the topics encountered in meditation (and by extension, of topics encountered elsewhere in life).
Meditative methods based in “pure observation” can cultivate a certain kind of passivity, where the meditator detaches herself from her experiences: a habit of experiencing, without exercising deliberate control over what she experiences.
“Mind-emptying” varieties of meditation do just what it says on the tin!
This is by no means an exhaustive list—neither of the various types of meditation that are out there, nor of all the consequences that typically result from the ones I’ve listed. But it begins to illustrate a wider point. All of these have the general character of habituating our mind/consciousness in some way or other. But in doing so, each of them set up very different habits and pattens, and they may incline us to different metaphysics; that is, our understanding of the self (who/what we are, considered “in ourselves” alone and in relation to a wider world) and the understanding we have of that wider world itself, its structure, and its nature.
In part, these results are “baked in” to the process. But in at least some cases (e.g., discursive meditation), it can also be the result of the specific themes that we choose for our meditations. Someone who regularly meditates on Epictetus may find himself becoming just a bit more Stoic in his approach to life, while meditation on the 211 propositions of Proclus’ Elements will understandably make a meditator much more inclined to see the world through the lens of Neoplatonic metaphysics. Diligent meditation on the mythic narratives of a particular religious or cultural tradition will likewise, in most cases, shift our own character and behavior ever so subtly in the direction of the heroic virtues embodied in those narratives. As the old saying has it, what you contemplate, you imitate.