I remember learning in school that the three branches of our Federal Government are "co-equal" - they balance and limit each other. The Founders did not want any one of the executive, legislative, or judicial branches to win a power struggle. Thomas Jefferson was concerned of the courts assuming the power of last judgment over all issues. Here is another of his quotes:
"To consider the judges as the ultimate arbiters of all constitutional questions [is] a very dangerous doctrine indeed, and one which would place us under the despotism of an oligarchy. Our judges are as honest as other men and not more so. They have with others the same passions for party, for power, and the privilege of their corps. Their maxim is boni judicis est ampliare jurisdictionem [good justice is broad jurisdiction], and their power the more dangerous as they are in office for life and not responsible, as the other functionaries are, to the elective control. The Constitution has erected no such single tribunal, knowing that to whatever hands confided, with the corruptions of time and party, its members would become despots. It has more wisely made all the departments co-equal and co-sovereign within themselves."
This is from a letter to William C. Jarvis in 1820. The two previous quotes just mentioned on this site were from 1804 and 1825, so one can see that this was an ongoing concern for Jefferson.
More of Jefferson's thoughts can be found on the University of Virginia site