Which is harder to do...

"What do you think, Ananda: Which is harder to do, harder to master — to shoot arrows through a tiny keyhole without missing, one right after the other, or to take a horsehair split into seven strands and pierce tip with a tip?"

"This, lord, is harder to do, harder to master — to take a horsehair split into seven strands and pierce tip with a tip."

"And they, Ananda, pierce what is even harder to pierce, those who pierce, as it actually is present, that 'This is stress'; who pierce, as it actually is present, that 'This is the origination of stress'... 'This is the cessation of stress'... 'This is the path of practice leading to the cessation of stres*s.'

"Therefore, Ananda, your duty is the contemplation, 'This is stress... This is the origination of stress... This is the cessation of stress.' Your duty is the contemplation, 'This is the path of practice leading to the cessation of stress*.'"

Vala Sutta-The Horsehair

* Four Noble Truths