In order for a Christian to bear fruit, he must be abiding in Christ. Furthermore, every branch that bears fruit must be purged in order to bear more fruit. This speaks of how the Lord uses trials and difficulties to perfect His people.
John.15.1-2I am the true vine, and my Father is the husbandman. Every branch in me that beareth not fruit he taketh away: and every branch that beareth fruit, he purgeth it, that it may bring forth more fruit.