The mind is the interface between the soul and reality. We are constantly being bombarded with stimuli and sensations from the world outside ourselves; the mind processes this onrush of sensations and determines which are to be taken note of, sorts and prioritizes them, and then decides what response is appropriate to what stimulus, based on past experiences or principles.
The way one's mind functions, then, is what determines how he relates to his environment. For a person to live maximally, he must provide his mind with proper categories in which to think, to process reality and relate to it. This is a fundamental purpose of Jewish meditation.
Through meditation, one takes the untamed mind and trains it to think in terms of images that are true and based on the Torah. By taking a subject through deeper and deeper levels of abstraction, one reaches and effects deeper and deeper dimensions of his mind, and thus gradually changes himself and the way he responds to the world around and within him.
To this end, the seasoned "meditator" will make use of the whole range of Biblical, Talmudic, Midrashic, Kabbalistic, Rabbinic, Chassidic and Jewish philosophical and ethical literature–as well as the innate structures of the letters of the Hebrew alphabet–to fertilize the potent ground of his imagination and faculty of association and produce a conceptual garden of ever-evolving multi-dimensional insights into reality. Where evaluated in the context of the above realms of knowledge, empirical information from nature can also be summoned to the same end.
The main mechanism of meditation is understanding the concepts themselves and establishing points of application between them and one's personal life. In addition, however, meditation is enhanced by hearing the holy words of the Torah (in Hebrew, the holy language, if possible) and simultaneously envisioning the holy letters, as though counting precious jewels one by one. True endearment to the letters comes from realizing that the Infinite One, blessed be He, has–so to speak–given Himself to us enclosed in them. To this end, each concept will be "anchored" to a specific source-quote either from the Bible or Rabbinic literature.