Repetition as a stylistic device is a direct successor of repetition as an expressive language means, which serves to emphasize certain statements of the speaker, and so possesses considerable emotive force.
As to the position occupied by the repeated unit in the sentence or utterance, we shall mention four main types, most frequently occurring in English literature:
1) anaphora – the repetition of the first word of several succeeding sentences or clauses (a …, a …, a …); 2) epiphora – the repetition of the final word (… a, … a, … a); 3) anadiplosis or catch repetition – the repetition of the same unit (word or phrase) at the end of the preceding and at the beginning of the sentence (…a, a …); The combination of several catch repetitions produces a chain repetition. 4) framing or ring repetition – the repetition of the same unit at the beginning and at the end of the same sentence (a …, … a). Repetition emphasizes the most important part of the utterance, rendering the emotions of the speaker or showing his emotive attitude towards the object described.
I would like to say about anaphora and give some examples:
Anaphora (an-NAF-ruh): Figure of repetition that occurs when the first word or set of words in one sentence, clause, or phrase is/are repeated at or very near the beginning of successive sentences, clauses, or phrases; repetition of the initial word(s) over successive phrases or clauses.
Examples:
"That my heart has been troubled, that I have not sought this nomination, that I could not seek it in good conscience, that I would not seek it in honest self-appraisal, is not to say that I value it the less. Rather, it is that I revere the office of the Presidency of the United States."
-- Adlai Stevenson, 1952 DNC Presidential Nomination Acceptance Address
"To raise a happy, healthy, and hopeful child, it takes a family; it takes teachers; it takes clergy; it takes business people; it takes community leaders; it takes those who protect our health and safety. It takes all of us."
-- Hillary Clinton, 1996 Democratic National Convention Address
"What we need in the United States is not division. What we need in the United States is not hatred. What we need in the United States is not violence and lawlessness; but is love and wisdom and compassion toward one another, and a feeling of justice toward those who still suffer within our country whether they be white or whether they be black."
-- Robert F. Kennedy, Announcing the death of Martin Luther King