We often use the term "defense" quite carelessly. When we attribute a defensive attitude to someone, it usually means that they do not share our perspective. However, boundaries are not inherently negative, as we could not exist without them. The author starts from the classical description of defense mechanisms and relates them to the elements and their corresponding behavioral patterns. The typical defensive attitudes expressed in the zodiac signs and planets are also examined. In the second part, Liz Greene particularly focuses on experiences with Saturn and Chiron. Rejection, loss, and injury mean that we erect barriers against life or against other people. The characteristic boundaries imposed by Saturn are discussed, with a particular emphasis on Saturn's constructive role.