firm-fixed in the heart

He is the Sage, the eternal Sun
Self-luminous, in whose presence this
Phenomenal world so variegated
And wonderful wholly disappears,
Unseen as other than the Self.

The Sage, exulting in the Self
And firm-fixed in the heart, regards
The universe as neither mere
Illusion nor as something other
Than the Self.

The whole world which we are aware of
Is by the Sage seen as Awareness
And nothing but Awareness only.
And knowing that there is no being
Except Awareness, he abides,
Rich in bliss, as Self-awareness.

~ Sri Muruganar, The Garland of Guru's Sayings, translation by Prof. K. Swaminathan

If 'I' also be an illusion, who then casts off the illusion?

Q: Is it not possible for God and the Guru to effect the release of a soul?

Sri Ramana Maharshi: God and Guru will only show the way to release; they will not by themselves take the soul to the state of release. Each one should by his own effort pursue the path shown by God or Guru and gain release.

Q: What is release?

Sri Ramana Maharshi: Inquiring into the nature of one's self that is in bondage, and realizing one's true nature is release.

Q: If 'I' also be an illusion, who then casts off the illusion?

Sri Ramana Maharshi: The 'I' casts off the illusion of 'I' and yet remains as 'I'. Such is the paradox of Self-Realization. The realized do not see any contradiction in it. You give up this and that of 'my' possessions. If you give up 'I' and 'Mine' instead, all are given up at a stroke. The very seed of possession is lost. Thus the evil is nipped in the bud or crushed in the germ itself. Dispassion (vairagya) must be very strong to do this. Eagerness to do it must be equal to that of a man kept under water trying to rise to the surface for his life.

Q: Cannot this trouble and difficulty be lessened with the aid of a Master or God chosen for worship? (Ishta Devata) Cannot they give the power to see our Self as it is to change us into themselves and take us to Self-Realization?

Sri Ramana Maharshi: Ishta Devata and Guru are very powerful aids on this path. But an aid to be effective requires your effort also.
Your effort is sine qua non (an indispensable or essential condition, element, or factor). It is you who should see the sun. Can spectacles and the sun see for you? You yourself have to see your true nature.