Singers use chants, or special hymns, when treating an individual who manifests physical, emotional, or mental problems. In ancient times, chants were performed by the sages who, in their meditations, heard perfect words and sounds which carried great wisdom. They then passed on this wisdom to their students by singing it. Chants are believed to contain pure sounds that create harmony and have healing power. In various cultures, individuals practice healing through the use of chants. These chants may be present during prayer or a number of rituals, to facilitate the healing process. In many cases, chants are spoken three times over the individual ailing. The number three is chosen because of its sacred power.