You can’t say A is made of B or vice versa. All mass is interaction.

“You can’t say A is made of B or vice versa. All mass is interaction.” is a brief expression attributed to Richard Feynman and used as an epigraph at the opening of Part II. Its decisive claim is that matter is not adequately described by reducing one thing to another: mass is framed instead as interaction.

Form and Meaning

The sentence begins by rejecting reduction in either direction: A cannot simply be said to be made of B, nor B of A. Its closing declaration shifts from that refusal to a positive account, naming interaction as what mass involves. The compact movement—from negation to assertion—makes relation, rather than an isolated substance, the statement’s organizing idea.

Placement in Part II

The expression follows the section marker “PART II” and the line “I held a jewel in my fingers.” Its placement makes it an opening frame for the section, while the jewel image supplies a concrete instance of something held and encountered. The passage does not explain the image or specify a physical theory; it places the material claim beside the image and leaves their connection open.

The Adjacent Epigraph

Immediately after the Feynman attribution, the text gives David Foster Wallace’s line, “We’re all lonely for something we don’t know we’re lonely for.” The pairing moves from a statement about mass as interaction to one about an unrecognized human lack. Both lines turn attention toward relations that are not obvious when considered in isolation, though the first addresses matter and the second loneliness. Together they set a relational emphasis for the section without spelling out a single interpretation.