Any form of worship which falls short of complete self-naughting will not take us to the unitive life. Faith, devotion, surrender are the means to it. Each individual has to achieve insight by his own effort after long and persistent practice.
When the veil of intellectual knowledge, of avidya, is swept aside, a flood of light breaks upon the awakened soul and a Universal Self is achieved.
When we rise in contemplation, when there is the vision of the Supreme which is entirely beyond the power of the soul to prepare for or bring about, we feel it is wholly the operation of God working on the soul by extraordinary grace. In a sense all life is from God, all prayer is made by the help of God’s grace, but the heights of contemplation which are scaled by few are attributed in a special degree to divine grace.
Dr S Radhakrishnan
(Source: From the introduction to The Principal Upanishads by Dr S Radhakrishnan)