Ruach (Roo-akh) Ha-Kodesh, a
Hebrew term literally meaning Spirit of Holiness, is a level of inspiration that is just below that of
Nevuah. According to the
Rambam in the Moreh Nevuchim (
Guide for the Perplexed,) this is simply an abnormally intense intellectual understanding, such that it is clear that it is from beyond you, but is still a purely
intellectual understanding that can be understood by others. This is not he level of
Nevuah, or true
prophecy. All the books of the
bible were written with
Nevuah, but the
Mishna and
Talmud were written with Ruach HaKodesh.
This term is also sometimes used, in a (gramatically) very odd sense, by christian missionaries, to refer to the holy ghost. and more grammatically correct way to do this would be Haruach Hakodesh.