Different scopes for spiritual progress
No scope:
To have any scope at all for spiritual progress one must be in the human realm. Some devas have potential, but it is much more difficult for them who know little of pain.
Low scope:
Here one knows the direction in which one should head, but lacks the strength to proceed. Realizing one's weakness in this life, one determines to invest in the future, working for the benefit of "future lives".
For example, a mother may know that Truth is attained through reason, but may lack the strength to practice reason in earnest herself. By way of compensation she can invest in the minds of her children by cultivating in their minds a genuine love of truth. She may well guide them towards the sciences, and towards an open-minded and questioning approach to life. Thus through her children she may redeem the past.
Medium scope
Here there is the strength and conviction of mind to want to relate to God on a truly personal level. But there is not the will to renounce the ego entirely. One wishes to retain some delusion, some ego, in order to enjoy life. Although there is a good comprehension of God, the clarity of mind to see God in His full glory is absent, so one is not privy to His powers.
High scope
The one of high scope has developed a deep disgust for all things worldly, and now has a clear vision of the Goal. He is determined to attain perfection quickly and at all costs. Such a one does not compromise. Nor does he fear pain, for he does not have enough faith in his own existence to be able to act in self-preservation. He holds nothing back; he sees all.
The difference between the high and medium scopes in infinite. It is like the difference between a person going to an auction prepared to bid his entire life's savings, and a person who upon entering the auction hall immediately bids his entire life's savings.