Machshavah

Machshavah, thought, is an innate tool a person uses to consciously tap into his ability to process intellect. The tools used to tap into and express the inner faculties of the soul [the intelectual and emotinal faculties] are refered to in Chassidic terminology as "Levushim," garments. "Thought," is the innermost garment which is most united and attached to the soul and its faculties. This tool is always in use.

Because it is the way a person consciously taps into his intellect this tool is refered to, in chassidic thought, as an expression [of the souls faculties] for himself [as opposed to speech which is an expression for the sake of someone else]. The medium used to think is letters. This 'garment,' the intellectual powers (Chabad) of a person are primarily expressed.Template:Citation needed

Unwanted Thougts

Being that "thought" is a garment that is united with the soul, therefore in Chassidic teachings there is special emphasis on the need for protecting this garment, not to think forbidden thoughts, because by corrupting the garment of thought, it can have a corresponding effect on the soul and its faculties.

The Alter Rebbe in Tanya, explains that when foreign thoughts arise in a person during prayer, one should not engage in elevating the qualities within them, since this guidance was only given to tzaddikim whose foreign thoughts fall to them from the evil thoughts of others in order to elevate them, and not to one who is himself sunk in the mire, as he cannot elevate thoughts while he himself is sunk in mire. The advice for this is to divert one's attention from these thoughts, and to regard them as if a gentile is standing over him to distract him during his prayers, for if he answers him, he will only encourage him to continue with his disturbances, and therefore one should not answer him - or them - neither good nor bad, until they disappear.

A Jew once complained to the Rebbe about foreign thoughts confusing him. The Rebbe replied to him: a. A well-known remedy for this first and foremost is to check his tefillin to ensure they are kosher according to law. b. Also, he should divert his mind from all thoughts that trouble him, not by fighting with them, but by transferring his thought to other matters, preferably to matters of Torah, since a little light dispels much darkness.