The practice and effort must be kept up so long as the sense of knower and knowledge persists - initial exalted states generally fade away.

(from "Reminiscences of Kunju Swami"):

Kunju Swami: One day I ventured to ask Bhagavan why those exalted states which I had first experienced in Bhagavan’s proximity began to wane and then were altogether gone when I left him and reached Kerala. By way of answer to my query, Bhagavan asked me to read verses 83 to 93 in the Tattuva Vilakka Padalam [‘The Exposition of the Truth’ Section] of Kaivalya Navaneetham, wherein lay the answer to my query:

"On hearing this, the disciple, loyal to the instructions of the Master, discarded the five sheaths and went beyond the blank, realised the Self as ‘I am Brahman,’ and remained as the Perfect Being.

At the glance of the Master who was Grace incarnate, the worthy disciple sank into the Ocean of Bliss and merged as the undivided Whole, as pure Consciousness free from body, organs and all else, with mind made perfect, and he became the true Self, experiencing the deep sleep state in the waking state.

After the blessed disciple had remained in that state for a long time, his mind gently turned outward. Then he saw his glorious

Master before him. His eyes were filled with tears of joy. He was full of love and fell at the feet of the Master. He rose up, came

round the Master, and with folded hands spoke to him:

“Lord, you are the Reality remaining as my inmost Self, ruling me during all my countless incarnations! Glory to you who assumed an external form in order to instruct me! I do not see how I can repay your grace for having liberated me. Glory! Glory to your holy feet!”

The Master beamed on him as he spoke, drew him near and said lovingly: “To stay fixed in the Self, without the three kinds of obstacles obstructing your experience, is the highest return you can render me.”

“My Lord! Can such realisation that has transcended the dual perception of ‘You’ and ‘I’ and found the Self to be entire and all-pervading, fail me at any time?”

The Master replied:

“The truth that ‘I am Brahman’ is realised from the scriptures or by the grace of the Master, but it cannot be firm in the face of obstructions.”

Ignorance, uncertainty and wrong knowledge are obstacles resulting from long-standing habits in the innumerable incarnations of the past which cause trouble, and then the fruits of realisation slip away. Therefore, root them out by listening to the Truth, reasoning and meditation. (sravana, manana and nididhyasana)

Checked by incantations, (sthambhana), fire will not scorch. Likewise, defective realisation will not put an end to bondage. Therefore devote yourself to hearing the Truth, reasoning and meditation, and root out ignorance, uncertainty and wrong knowledge.

Ignorance veils the Truth that the Self is Brahman and shows forth multiplicity instead. Uncertainty is the confusion resulting from lack of firm faith in the words of the Master; the illusion that the evanescent world is a reality and that the body is the Self, is wrong knowledge.

So say the sages. Listening to the Truth is to revert the mind repeatedly to the teaching: ‘That thou art’. Reasoning is the rational investigation of the meaning of the text, as already heard. Meditation is the one-pointedness of mind. If every day you do these, you will surely gain liberation.

The practice must be kept up so long as the sense of knower and knowledge persists. No effort is necessary thereafter. Remaining as the pure, eternal Consciousness, untainted like the ether, and thus liberated while alive, one will live forever as That — after being disembodied also"