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.
Unwanted Thougts
Being that "thought" is garment united with the soul, and therefore in Chassidic teachings** there is special emphasis on the need for special protection of this garment, not to think **forbidden** thoughts, because by corrupting the garment of thought, the soul is also damaged. In this 'garment,' the intellectual powers (**Chabad**) of a person are primarily expressed.
According to the approach of the **Alter Rebbe** in the **Tanya**, 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 a **gentile** standing over him to confuse him during the **Amidah prayer**, 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.[1]