This quotation is taken from one of Ralph Waldo Emerson's much lesser known works -- an essay that he wrote about Napoleon. Here is some more of the passage -- it can help us understand and discuss what is being said here:
Bonaparte was the idol of common men because he had in transcendent degree the qualities and powers of common men. There is a certain satisfaction in coming down to the lowest ground of politics, for we get rid of cant and hypocrisy. Bonaparte wrought, in common with that great class he represented, for power and wealth,- but Bonaparte, specially, without any scruple as to the means.
So what Emerson is claiming here is that a politician like Napoleon is refreshing because he does not pretend to be high-minded. He is like a common person in that he does not try to disguise what he wants -- he is openly trying to get power and wealth.
I suppose that in our own day, we could compare this to people's feelings about someone like Sarah Palin. The idea here is that she, unlike so many politicians, is not really trying to hide what she wants. She is coming out and saying what she wants in a straightforward way.
I would argue that this is something that we should want in our politicians. It would be satisfying if they came out and said what they meant rather than trying to sound like they agreed with everyone. I do not know if anyone could get elected that way, but it might get us started towards having more respect for politicians if they seemed honest.
Please note that the word "cant" here does not mean "cannot." Instead, cant is something like a cliche or a canned saying that people use without really meaning it. That is why cant and hypocrisy go together.
If we are examining the quote in terms of meaning, I think that there are several approaches which can be taken on it. The first would be that the idea of "lowest ground" of politics. On one hand, this can be seen as highly democratic in that everyone is involved in the process of decision making. On another level, there might be a fear in not desiring to raise the level of discourse to its highest end. If we are examining the quote's second premise about "can't" and "hypocrisy," there might be some level of affirmation here, as well. Political dialogues find themselves occupied by these two dimensions. The danger of hypocrisy in politics is that is brings about duplicity and a lack of authenticity. I think that it might be a bit too optimistic to presume that this is eliminated with the "lowest" ground of politics, as its presence might be inherent within all domains of political discourse. When we examine, "can't" and the hopeful elimination of it, perhaps this, too, might be too optimistic because there is always a level of negotiation in politics that will leave some side unhappy. In the end, I think that there might be a hopeful element to the assertion in the quote, but might not be entirely present.