Searching for a Thesis Quote

My PhD thesis is almost finished and hopefully I will submit it within a few weeks. The most important thing lacking, at the moment, is a suitable quote for the beginning. I hereby enlist the help of my readers for suggestions!

I guess I should say something about the topic of the thesis and what kind of quote I am looking for. The topic of the thesis is particle detectors in quantum field theory. I have given a nontechnical explanation in this old post, but if you don't care to go and read it, enough to say that it is about the possibility of defining the "particle content" of quantum fields operationally, by the energy transitions an interaction with the quantum field can produce on another quantum system such as an atom. If an atom interacting with a field gets excited, you can say that it has absorbed a field quanta or "particle". This is important because in a curved spacetime context there are usually no other "intrinsic" definitions of particles available. My work concerns more precisely the question of giving a rigorous definition of the transition rate of such a detector, which is not as simple as it sounds. You can read the details in my last paper.

For the beginning of the thesis, I do not want a prosaic quote from a physicist about these matters. My ideal would be a poetic, literary or philosophical quote that could, with an effort, be read as alluding to this topic (even though this was obviously not intended). As an example of the kind of thing I like, my undergraduate thesis concerned calculation of vacuum energy of quantum fields in a class of spacetimes. As the reality of quantum field vacuum energy means that there is no real vacuum in Nature, that anything that looks empty really has a "zero-point energy", I used a quotation from Parmenides, the Pre-Socratic philosopher that based his philosophy on denying the reality of Not-Being:

That things which are not are, shall never prevail, she said,
but do thou restrain thy mind from this course of investigation.
And let not long-practised habit compel thee along this path,
thine eye careless, thine ear and thy tongue overpowered by noise;
but do thou weigh the much contested refutation of their words,
which I have uttered.

The Spanish translation I used is much more poetical, for those that can read it:

Pues nunca dominará esto: que haya no ser. Aleja tú
el pensamiento de este camino de investigación,
y que la inveterada costumbre no te obligue, a lo largo
de este camino, a utilizar el ojo que no ve, el oído que
resuena, y la lengua; juzga con la razón la combativa
refutación que te he enunciado.

Besides the rejection of Not-Being, the quote was appropiate for talking about "investigación", which in Spanish means "research" besides "investigation", and is used everyday in scientific context. Also, the rejection of the senses in favour of reason can be seen (with a slant) as endorsing theoretical physics over experimental.

So this is the kind of thing I would like. At the moment, my best candidate is the following quote from Bertrand Russell's An Outline of Philosophy:

'Matter' is a convenient formula for describing what happens where it isn't. I am talking physics, not metaphysics; when we come to metaphysics, we may be able, tentatively, to add something to this statement, but science alone can hardly add to it.

Reasons why this quote is appropriate are that (although he was not exactly talking about the same thing) Russell seems to be endorsing the operational definition of particles my thesis is about; that the ending of the quote looks ironical as a preface to a hundred pages "adding to it" from a scientific point of view; and that An Outline of Philosophy is a very dear book to me, being the first real philosophy book I read. Rereading it recently I found it full of things I could not accept, either scientifically outdated or philosophically unsound; but its general spirit of approaching philosophy in a way closely related to and interwoven with science is one that I still admire. Reason counting against this quote is that it is a bit too prosaic; I would like something more dramatical and unexpected. Russell is so well-known in the scientific community that quoting him is only slightly less predictable than quoting Einstein or Feynman. But still for the moment this is the best I have found.

Any suggestions...?