Habib Abd al-Qadir al-Saqqaf (may Allah have mercy on him and benefit us by him) explains how we are affected by the spiritual state of those around us.
Every person has rays which emanate from their soul. You receive these rays when you come close to them or sit in their presence. Each person’s rays differ in strength according to the state of their soul. This explains how you become affected by sitting in the presence of great people. They are people who follow the way of the Prophets in their religious and worldly affairs. When they speak, they counsel people. Their actions guide people. When they are silent they are like sign posts which guide people along the path, or like lighthouses whose rays guide ships. Many of them speak very little, but when you see them or visit them you are affected by them. You leave their gatherings having been enveloped in their tranquillity. Their silence has more effect than the eloquent speech of others. This is because the rays of their souls enter you.