Hi Sanya, In the original text, "how" is italicised. This tells me that this phrase is not a typical way of expressing the idea, an dis probably new. (Another way is using quotation marks.) Basically, yes it is a noun, but the sentence is not written in a typical way. I would replace "how" with "manner".

That sentence, as it stands, makes no sense. What is the context? Also, is "how of thought" in quotes (as I've written) or otherwise set apart, like with asterisks or italicized, because it's not being used grammatically.