Original: Freud is best known for his theories of the unconscious mind and the defense mechanism of repression , and for creating the clinical practice of psychoanalysis for treating psychopathology through dialogue between a patient , technically referred to as an '' analysand '' , and a psychoanalyst .
Simplified: He was born as Sigismund Schlomo Freud , but in 1877 at the age of 21 he changed his name to Sigmund Freud .