The rapid production, dissemination and disappearance of information in the age of social network fundamentally changed the life of university student. The fragmentation of knowledge caused by this process forms a new challenge to the traditional teaching model of architectural history. Facing this challenge, this essay argues that it is necessary to strengthen the belief in the constant and deep value of architectural thought, in contrast to the superficiality prevalent today. As to the concrete measure, this essay suggests an enhancement of the introduction and utilization of the unit ideas of western thought, a concept proposed by Arthur Lovejoy. These ideas could be incorporated into the analysis of classical works and the theories of crucial architects. This essay uses Sullivan’s famous phrase “form follows function” as an example to show how the unit idea of Aristotelian teleology could help to disclose Sullivan’s real intention. And finally, it is argued, unit ideas could contribute to the clarification of history, increase the depth of historical teaching and as a significant instrument, counterbalance the tendency of fragmentation and superficiality.