In some cases, in the relationship between a father and a son, it is better for the father to achieve no more than mediocrity in certain fields. His unparalleled excellence in a single field could serve as an impediment to his son.
If, however, he limits his personal achievement, he is able to gain his son’s interest in a particular field, and then give his son the opportunity to surpass him. So in some ways, and at some times, it may be best for a father to hold himself in check.