Sertillanges situates the purpose of the intellectual vocation where it belongs -- as just another part of life.
All other areas of work aim to help others and the intellectual life is no different. We are trying to feed intellects, providing the deep thought that daily activities prevent the average person from doing much of. For Sertillanges, this is a real participation in the priesthood of Christ. We must “work as Jesus meditated, --as He drew on the life-springs of the Father to pour them out on the world.” This requires a deep connection both with God and with others that Sertillanges describes as working “with the feeling for man, his needs, his greatness, and the solidarity which binds us closely together in a common life.”
Without a doubt, this perspective excludes the individualist intellectual who attempts to sit “outside” of humanity so that he has a more “objective” view of his “subject matter.” I saw this in my undergraduate studies as a religion major and I’m sure it is common in other disciplines since the idea of scientific detachment from your subject matter is pervasive. In the case of religion, identifying with the subject matter is crucial. Walking inside the shoes of a religious believer is going to reduce “objectivity” in one sense, but, unless we are really close to people, sympathizing with them, believing them, then we will never understand the truth from their perspective. We won't be “objective.” You should be a close observer in danger of falling in love with the subjects of your study, no matter how bad they seem. Avoiding the individualist trap, helps prevent the tendency for intellectuals to create “art for art’s sake.” Or, art for other intellectuals' sake--work written for those sufficiently detached from the experience of the common person.
Ensuring that we have the "feeling for man" requires writing with “the idea of some utilization." It requires you to "pick out certain individuals or certain groups whose need you know, find out what may bring them out of their night and ennoble them..." This can seem like a daunting task especially if you're in a very theoretical field. I think the best place to start is to see what other professors in your area might be doing. Where do they speak? What associations are they a part of? Finding real people to serve with your intellectual work will also help you to stay focused on this time period rather than getting caught up in the past or the future. The real benefit, though, is the satisfaction that comes from helping real people have "epiphany moments."