Each field of study has central, core knowledge, and a broader area of peripherally-related knowledge. As research in each field continues, gradually that peripheral area expands, and will at some point overlap with other fields. The core, too, will shift through research, and when the core areas of two fields intersect, a new field is born.
每一個學門都有核心知識和邊緣知識，經過不斷研究，各學門領域都會擴大，並逐漸和其他領域重疊，原來核心的部分也在轉移，當二個核心結合在一起時，就出現學術新領域。