There are many principles in the Constitution, each with its own limitations. Let us look at two important principles and examine their limitations.
One principle is the principle of majority rule. This is a basic principle of democracy, but it has its limitations. For one thing, it is limited by the existence of a Supreme Court. This court consists of unelected people who can thwart majority rule. They can do so because the Constitution itself is set up to limit majority rule. The Constitution sets out all sorts of things that the majority cannot do (such as limiting free speech).
This brings us to a second principle, that of limited government. The Constitution is explicitly set up to ensure that government will not be able to do certain things (again, like limiting free speech). But there are limits to this principle as well. Free speech and other rights will only be protected so long as some part of the government has the will to protect them. This often fails when the people in question are particularly unpopular. Thus, we saw limitations on free speech, for example, during WWI and during the 1950s when there was a great fear of communism.
In these ways, two of the most basic principles in the Constitution have limitations.