These three separations correct blemishes in the three worlds of Thought, Action and Speech. Hair grows from the head, the seat of thought. Thus, cutting the hair represents correcting imperfections in the sphere of thought. Tumah corresponds to the sphere of action. The principal source of Tumah results from contact with a dead body, for before its passing, the body was the epitome of life and action.
Wine represents the function of speech.
Secrets are communicated by words. Correction in the sphere of speech is effected by abstinence from wine. Speech combines both thought and action, soul and body. Speech is a synthesis of the non-physical and the physical. For without thought there can be no speech, and without the movement and shaping of the lips, there can be no issue of words.