"We do not need to proselytise either by our speech or by our writing. We can only do so really with our lives. Let our lives be open books for all to study"

Mahatma Gandhi is suggesting that the best way to spread our beliefs and values is not through words, but through our actions. He thinks that our lives need to be an example to others, and that our habits should be a testimony to our beliefs. He is saying that we ought to not try to encourage others to think what we believe, however rather that our lives ought to be an open book for others to observe and learn from. He is stressing the significance of living a life that follows our worths and beliefs, which this is the best method to spread our message. He is recommending that our words and works are not as effective as our actions, and that our lives should be the primary source of influence.