According to Freud, during the first 18 months of life, the dominant source of erogenous pleasure is the "Mouth".
Freud whose actual name was Sigismund Schlomo Freud, popularly known as Sigmund Freud, born in 1856 in Austria is known to be the founder of psychoanalysis which refers to a method of healing by talking to the patient. He was a neurologist who passed away in 1939.