To gain entire likeness to Christ, I ought to get a high esteem of the happiness of it. 

I am persuaded that God's happiness is inseparably linked in with his holiness. Holiness and happiness are like light and heat. God never tasted one of the pleasures of sin. Christ had a body such as I have, yet he never tasted one of the pleasures of sin. The redeemed, through all eternity, will never taste one of the pleasures of sin; yet their happiness is complete.... Every sin is something away from my greatest enjoyment... The devil strives night and day to make me forget this or disbelieve it. He says, Why should you not enjoy this pleasure as much as Solomon or David? You may go to heaven also. I am persuaded that this is a lie - that my true happiness is to go and sin no more. 

Robert Murray M'Cheyne. Biography compiled by Andrew Bonar.