A pleasing thing about the parable of the Vine and the Branches is the way it reveals the way that the Natural world and the Supernatural world come from the same creator. The life of the vine in the world of Nature depends entirely on the sap’s reaching the branches, while the life of a soul in the Supernatural world relies entirely on our availing ourselves of God’s grace.
The old-time Catholic explanation of the parable would be that we cannot bear spiritually meritorious fruit if we are not in the state of Sanctifying Grace. There is no arguing with that, however it limits what Jesus meant to teach by his parable.
We should turn to the Book of the Prophet Isaiah, Chapter Eleven, where the Messiah is described as one whose activities exemplify Wisdom, Understanding, Counsel, Fortitude, Knowledge, and Fear of the Lord.
For our active life to be one that bears much fruit, our dependence on the vine should also constantly be drawing on him for Wisdom, Understanding, Counsel, Fortitude, and Fear of the Lord.