Sentence:  I wonder whether they [women] ever <WSD>blush</WSD> at those things by themselves, at which they have so charming a knack of <WSD>blushing</WSD> in company.—If not; and if <WSD>blushing</WSD> be a sign of grace or modesty, have not the sex as great a command over their blushes, as they are said to have over their tears? 
Meaning of the word marked with <WSD> tags:  To become red in the face (and sometimes experience an associated feeling of warmth), especially due to shyness, shame, excitement, or embarrassment.