The swan was seen as a traditional symbol of beauty and grace in ancient Greece, and was sacred to Aphrodite. The swan was also sacred to Apollo, the god of music (among other things), in Greek mythology. At the time, the people believed that the swan sang a sweet and beautiful song when people died.
For example, in case of monatomic gas it is just a kinetic energy of motion of atoms of gas as measured in the reference frame of the center of mass of gas. In case of molecules in the gas rotational and vibrational energy is involved.
Radiant energy is a form of kinetic energy. Kinetic energy refers to the movement of the energy whether is is of atoms, molecules, waves, substances or objects. Other forms of kinetic energy include thermal energy, sound, motion energy and electrical energy. Without radiant energy, like that from the sun, life on Earth would not be possible. Radiant energy is the result of a change in configuration of electrons. It can travel through any substance including air, liquid, glass, and space. However, matter is not necessary for transmission of radiant energy. Even in a vacuum environment, radiant energy can move.