David used to say that the spiritual development was like working in a feather warehouse. That on the first day of employment the foreman took you to a huge pile of feathers and instructed you to move them one at a time across to a huge beam scale with a thousand pound weight, with the instructions to come get him when the scale tilted.
And I have learned that the essentials of diligence, consistency, faith are learned.
That the scriptures from many masters concede that the desired for, is realized when all attachment is relinguished. On David's scale that would be beyond thought and reason of the intellect. I suspect the " I " attachment {identification} at the 400-500 detains many for a long time. There seems to be a traumatic experience that precedes each new spiritual vista. The A Course in Miracles, T31:IV " The real Alternative" suggests in the first several paragraphs the pathways of the world that lead ultimately nowhere except back into themselves. The Course's perception of this would be paralleled with the Yogi's "Maya" and the "Man in the maze" symbol of the Hopi's. However the Course shares that there is a ultimate purpose that will be realized beyond the hypnosis upon this time/space experience , provided that the experiencer choses to not die upon seeing it's utter hoplessness! This ,I believe has a parralel in the method utilized by the Zen masters. Here I will only point to D.T. Suzuki's "Essays in Zen Buddhism" vol 1.
Above 500 the intellect can be brought into service of the heart. I suspect until sufficient purification is achieved the heart remains as a servant to the intellect. The devine desires to return to wholeness. Paradise lost, paradise regained. Please note that in the bibical account that it was the forbidden fruit was from the "tree of the knowledge of good and of evil." Obviously a thought of "need" entered into the mind that otherwise only knew "wholeness," hence dualality was created. And I postulate is constantly being created, moment by moment. Cessation of that creation, or better mis-creation allows the timeless to be known. Wholeness is the reality. Need, it it's anti-thesis, which is a no thing, a state of mis-identification. The Course say's "We need do nothing." Lao Tzu's opening stanza, "The Great Tao Can not be spoken of." Stillness returns to the mind.