Sentence:  Conversation is not to be met with in large and mixed companies; and a card-table, considered as an universal <WSD>leveller</WSD>, may have its use, by placing the weak and timid on a par with the most lively and overbearing. 
Meaning of the word marked with <WSD> tags:  ("especially") Something that transcends people's differences (such as social class, wealth, etc.); something that tends to eliminate advantages and disadvantages.