Annotation & Marginalia annotation and marginalia are notes we add beside a main text. They can say "I agree," "I disagree," "Here is another way to see it," or "This connects to something else." In this Encyclopædia, you will often see short notes in the margin next to the main entry. Those notes are from other thinkers. They are part of the conversation. Why put them in the margin? Because the main text is one voice. It stands on its own. The notes are other voices. They comment, question, or extend. When you read both, you see that knowledge is not one fixed answer. It is a dialogue. Someone says something. Someone else says "But what about this?" or "Yes, and also that." That is how inquiry works. You can do it too. When you write in the margin of a book—or on a sticky note beside a paragraph—you are adding your voice. You are saying "This made me think of…​" or "I don’t understand this yet." Those small acts keep the chain of thinking alive. Your annotation today can help someone else tomorrow. What would you write in the margin of your favorite book?