Epimedium, also known as "Horny Goat Weed," is widely considered to be a powerful aphrodisiac. It gets its nickname from the observation that goats, after consuming this herb, begin to copulate. Epimedium tonifies Kidney Yang and has the ability to strengthen the bones and structural system of the body, including the joints, lower back, and knees. According to the "Classis of Materia Medica," Epimedium can help with "old-age confusion and middle- age forgetfulness." Other ancient classics have stated that Epimedium "augments the essential Qi, and is an herb of the arm and leg Yang brightness, Triple Burner, and Gate of Vitality. It is appropriate for those with insufficiency of true Yang.