Source: Talks with Sri Ramana Maharshi
Devotee: Should one have a form in one's mind, supplemented with reading or chanting God's name in one's meditation?
Bhagawan Ramana Maharishi.: What is mental conception except it be meditation?
Devotee: Should the form be supplemented by repetition of mantras or dwelling on divine attributes?
Bhagawan Ramana Maharishi.: When japa is the predominating tendency, vocal japa becomes eventually mental, which is the same as meditation.