What precisely is our purpose? If we do not know the answer, we are wearing ourselves out for nothing. A traveler without a route suffers all the exhaustion of his journey and gets nowhere. The aim of our journey is the kingdom of God, the kingdom of Heaven. And our purpose must be purity of heart, for without this, no one will gain the kingdom. Let us fix our mind on purity of heart; this will plot our path and enable us to run straight ahead, confident of where we are heading. And if our thoughts sometimes stray, let us return to this purity at once. This one aim will set us on a straight path, so that all our effort will contribute to our single goal.
– John Cassian