From Nandakowada Sutta

"Just as when the oil in a burning oil lamp is inconstant & subject to change, its wick is inconstant & subject to change, its flame is inconstant & subject to change, its light is inconstant & subject to change. If someone were to say, 'The oil in that burning oil lamp is inconstant & subject to change, its wick is inconstant & subject to change, its flame is inconstant & subject to change, but as for its light, that is constant, everlasting, eternal, & not subject to change': would he be speaking rightly?"


"No, venerable sir. Why is that? Because the oil in that burning oil lamp is inconstant & subject to change, its wick is inconstant & subject to change, its flame is inconstant & subject to change, so how much more should its light be inconstant & subject to change."


"In the same way, sisters, if someone were to say, 'My six internal media are inconstant, but what I experience based on the six internal media — pleasure, pain, or neither pleasure nor pain — that is constant, everlasting, eternal, & not subject to change': would he be speaking rightly?"


"No, venerable sir. Why is that? Because each feeling arises dependent on its corresponding condition. With the cessation of its corresponding condition, it ceases."


"Good, good, sisters. That's how it is for a disciple of the noble ones who has seen it as it actually is with right discernment.


"Just as when the root of a great, standing tree — possessed of heartwood — is inconstant & subject to change, its trunk is inconstant & subject to change, its branches & foliage are inconstant & subject to change, its shadow is inconstant & subject to change. If someone were to say, 'The root of that great, standing tree — possessed of heartwood — is inconstant & subject to change, its trunk is inconstant & subject to change, its branches & foliage are inconstant & subject to change, but as for its shadow, that is constant, everlasting, eternal, & not subject to change': would he be speaking rightly?"


"No, venerable sir. Why is that? Because the root of that great, standing tree — possessed of heartwood — is inconstant & subject to change, its trunk is inconstant & subject to change, its branches & foliage are inconstant & subject to change, so how much more should its shadow be inconstant & subject to change."


"In the same way, sisters, if someone were to say, 'My six external media are inconstant, but what I experience based on the six internal media — pleasure, pain, or neither pleasure nor pain — that is constant, everlasting, eternal, & not subject to change': would he be speaking rightly?"


"No, venerable sir. Why is that? Because each feeling arises dependent on its corresponding condition. With the cessation of its corresponding condition, it ceases."


"Good, good, sisters. That's how it is for a disciple of the noble ones who has seen it as it actually is with right discernment.


"Just as if a skilled butcher or butcher's apprentice, having killed a cow, were to carve it up with a sharp carving knife so that — without damaging the substance of the inner flesh, without damaging the substance of the outer hide — he would cut, sever, & detach only the skin muscles, connective tissues, & attachments in between. Having cut, severed, & detached the outer skin, and then covering the cow again with that very skin, if he were to say that the cow was joined to the skin just as it had been: would he be speaking rightly?"


"No, venerable sir. Why is that? Because if the skilled butcher or butcher's apprentice, having killed a cow, were to ... cut, sever, & detach only the skin muscles, connective tissues, & attachments in between; and ... having covered the cow again with that very skin, then no matter how much he might say that the cow was joined to the skin just as it had been, the cow would still be disjoined from the skin."


"This simile, sisters, I have given to convey a message. The message is this: The substance of the inner flesh stands for the six internal media; the substance of the outer hide, for the six external media. The skin muscles, connective tissues, & attachments in between stand for passion & delight. And the sharp knife stands for noble discernment — the noble discernment that cuts, severs, & detaches the defilements, fetters, & bonds in between.