Barack Obama said:

"The study of law can be disappointing at times, a matter of applying narrow rules and arcane procedure to an uncooperative reality; a sort of glorified accounting that serves to regulate the affairs of those who have power--and that all too often seeks to explain, to those who do not, the ultimate wisdom and justness of their condition.

But that's not all the law is. The law is also memory; the law also records a long-running conversation, a nation arguing with its conscience."

What did he mean by that?