Help With Atlas Shrugged Quote

Hello,

I am writing a paper on philosophy and I remember something from Atlas Shrugged to the affect of:

Study two things, philosophy to know how the world should be and physics to know how it is.

or

We study philosophy so that we may know how to think, and we study physics so we may know what to think.

 

Can anybody help me find where the quote comes from?  I can’t find it anywhere.

I don’t have an exact citation, but it comes from the valley sequence, when Dagny spends an evening with some of the inhabitants.  Hugh Akston says this is why his star pupils (John, Ragnar and Francisco) studied both subjects.

Thank you very much sir.  I will start reviewing that part of the book.  I was starting to wonder if I was imagining things, because when I was searching through my pdf version, I couldn’t find anything.

From the valley:

They were majoring in two subjects: physics and philosophy. Their choice amazed everybody but me: modern thinkers considered it unnecessary to perceive reality, and modern physicists considered it unnecessary to think. I knew <as_726> better; what amazed me was that these children knew it, too.… Robert Stadler was head of the Department of Physics, as I was head of the Department of Philosophy.

 

<as_726> Atlas Shrugged, page 726