Four Stages of Spiritual Evolution was mentioned by T.Rajarathinam, in a discourse.
There are said to be four stages in spiritual evolution.
The first is to do with rituals.
The second is to do with the recitation of mantras.
The third involves yoga.
The fourth is the most evolved stage of gnana.
A fruit begins its journey as a bud. The bud blooms into a flower, which then becomes an unripe fruit and ripens later.
Likewise, ritualistic worship is like a bud. Worship through mantras is like a flower. Yoga is the unripe fruit, and the ultimate stage of gnana is the ripe fruit.