For receiving the Guru’s grace we must make ourselves worthy. The sun is always shining but clouds sometimes prevent it rays from reaching the earth. When the clouds clear away, the sun’s rays flood the earth. When the mind of an individual is not attuned to his Guru and is shrouded by other thoughts, the thought vibrations from the Guru can’t reach the disciple and so they do not have any effect on him. Only when mind is completely concentrated on the Guru, the vibrations touch him leading to beneficial results.