Spiritual progress requires active effort: As a rule, the person who has entered the spiritual path gradually advances until he attains the goal; this does not apply to those who have not definitely entered the path or have no Master to guide them. Through their chaotic pursuits of several lifetimes, most persons are likely to go further away from the goal by the heaping up of binding sanskaras. Hence spiritual progress cannot be said to be automatic, in the sense that it will come about without the active effort of the person concerned.
Danger of falling back: Sooner or later, however, the logic of experience gathered through several lives drives everyone to enter the path and seek the highest goal. Once the aspirant enters the path, he usually goes forward with steady progress. As he advances on the path, he often develops certain latent capacities that enable him not only to experience consciously the inner subtle and mental worlds but also to manipulate the forces and powers available on the higher planes of consciousness. Yet, the crossing of the first few planes does not necessarily ensure safe and steady progress. There are many pitfalls on the path itself, and unless there is the assured guidance of a Master, the aspirant is in danger of falling back.
–Discourses 7th Ed., p336