The speed of enlightenment depends on people's wisdom and spiritual faculties.

Question: When a hand touches an electric current and gets shocked into numbness and trembling, does this count as realizing the electric current? When a blind person touches a light bulb with his hand, has he realized the lamp? Can he realize the lamplight?

Answer: Whether it counts as realization depends on the specific circumstances; it varies from person to person. For example, when a scientist gets an electric shock, he knows the principles of electric current one hundred percent—his realization is very profound, comparable to the seed-wisdom (bīja-jñāna) of Consciousness-Only in Buddhism. When a small child gets an electric shock, he may not necessarily know why this phenomenon occurs; even if he knows he was shocked and will avoid it next time, he still may not understand the principles of electric current, nor necessarily understand its functions. When a blind person's hand touches a light bulb, he may not necessarily know it is a light bulb. First, he must have the relevant concept of a light bulb—he must have seen a light bulb before going blind, or someone must have told him what a light bulb looks like—only then can he know it is a light bulb. Otherwise, no matter how many times he touches the light bulb, he will not know what it is. Sentient beings have been dealing with the tathāgatagarbha since beginningless kalpas; they live within the tathāgatagarbha and use it at every moment, yet they do not know that the tathāgatagarbha exists, nor do they know what the tathāgatagarbha looks like.

The Sixth Patriarch heard a single sentence and attained enlightenment, whereas others might hear a hundred sentences of explanation about that sentence and still remain far, far away from enlightenment. The key lies in the person himself; wisdom and spiritual faculties (indriya) are extremely important. An arhat hears a single sentence spoken by an unenlightened worldling who studies Buddhism and realizes the fourth fruit; a worldling may study the Āgamas for a hundred years and not even attain the direction of the first fruit. There is no basis for comparison between one person and another.