Success is tricky, and not only because achieving it demands talent, discipline, opportunity and often a little luck.

It is tricky to define success precisely: Metrics to identify a successful parent will not be the same as those to assess a great CEO. Nevertheless, we might call it "masterful execution" that results in a good outcome, as well as in status or recognition. Yet the concept remains tricky because we can be fooled into thinking that success is the completion of our travels, rather than the beginning of a more profound journey that leads to something greater — significance.

In fact, in careless hands success even creates a sort of prison where we cannot break free of our own ego, where we are chained to our own small desires, comforts and concerns. In this way, success, by feeding the ego, leaves us isolated from our better nature, even as it elevates us to positions of authority where, with wisdom and compassion, we could effect meaningful change. The material rewards that accompany success, while in themselves perhaps deserved, may divert us until we are oblivious to others' needs.

Yet success, when understood properly, is the necessary foundation for significance, and significance involves making a difference through action that takes us beyond the limits of ourselves to contribute to the greater good. If success requires gathering resources inward to one spot (i.e. the individual), significance involves a distribution of a person's gifts outward into the world.

At the Kellogg School, we prepare our students to achieve both success and significance. The two are not mutually exclusive; indeed, you cannot hope to make a real impact without first gaining professional stature. This is why our goal is to ensure that Kellogg is not only the best business school in the world, but also the best business school for the world.

In addition to boasting a broadly excellent curriculum, we offer students majors like Social EnterprisE at Kellogg (SEEK), designed to create global leaders who manage diverse stakeholder groups in the service of positive social development.

Our vigorous student culture challenges people to be co-creators of their academic experience, inside and outside the classroom. To that end, Kellogg students participate in a rich variety of extracurricular activities, including clubs and conferences. They also engage the community through organizations like Business with a Heart, the umbrella group for various service programs at the school. Hundreds of students are also involved in the nationally recognized Social Impact Club, whose mission is to support and inspire Kellogg students to apply their management skills in the nonprofit, public and private sectors.

Our students also demonstrate a keen interest in environmental sustainability, with clubs and events to educate and enlighten others about this subject. And with efforts like the Global Health Initiative, Kellogg students, faculty and staff are making extraordinary differences by developing innovative solutions to global health concerns and extending the reach of new healthcare technologies. Teams from Kellogg and Northwestern, with the support of a four-year grant from the Bill and Melinda Gates Foundation, are currently fighting HIV/AIDS in Africa.

These are just a few of the efforts that demonstrate our desire to provide the experiential learning opportunities that hone our students' skills while also broadening their perspectives about the responsibilities that face global leaders. In other words, at Kellogg the tools of success merge with a culture of caring that reinforces the importance of service to others. This model is one I personally endorse.

I also believe in four stages of life: study, success, significance and sacrifice. Each lasts about 25 years and follows logically from the other.

Early in life is the time of study, preparing oneself for future service by accumulating the education that will enable the next stage — success. In this second part of life, the person turns the lessons of youth into action and a livelihood that supports one's family and society.

From here comes significance, where one leverages resources gained through a successful career so that these can create broader social benefit. The person seeks more meaningful ways to contribute to the community. This stage is marked by a transition from a materialist focus to a more spiritual one.

The final stage of life, sacrifice, features a deeper move into contemplation, shaking off conventional attachments in favor of cultivating a path that produces wisdom.

Through these stages one sees a gradual diminution of the self, replaced by a desire to pay more attention to the needs of others. Personal freedom comes when we move away from exclusive concern with ourselves and regard others as worthy of our talents and time.

In the profiles that follow, you will meet some Kellogg School graduates who are pursuing this path. They have cultivated their leadership skills to achieve professional success, but they also have gone further, reaching out to help others. Their efforts to make a difference take various forms. What is similar in each person is a desire to solve problems and make the world a better place.

The wealth of one who gives is undiminished. When leaders concentrate their efforts outside themselves, to benefit society, this is when they fulfill their purpose and reap their true reward.