We read the Tochacha, the evil that will befall the Jewish people if they abandon the Torah. Immediately following this portion we read the laws pertaining to the values of people in various stages of their lives if they are eager to contribute their value to the sanctuary. Why the juxtaposition of these two passages?
A wonderful explanation was given by a great Rabbi. After reading the Tochacha and the dire horror that is predicted, one may loose all sense of his personal worth. How can he feel that his life has any value if such disastrous and dreadful predictions threaten him?
Hence the Torah sends a word of encouragement. Every person has value. The Tochacha is a declaration of what will happen to him for disregarding the Torah, but it does not diminish the value of a person. We must all live up to the potential we are granted when we are born. Everyone is different and everyone is obligated to live up to his own promise.