(I don't have formal training in philosophy; I'm a physicist who really likes The Myth of Sisyphus; other commenters on this forum will no doubt give you a better placement of this sentiment in philosophical traditions. This is how I understand that passage in relation to the rest of the work.)
Camus's Myth of Sisyphus is concerned with what he calls the absurd, an experience which is basically founded in a paradox between two bedrock elements of the human experience: a desire to understand the world, that is, to perceive some order that underlies everything, and at the same time the ultimate inability of humans to do so. Key point -- the absurd isn't "things happen without meaning" it's that things happen without meaning yet we are built to seek meaning. Hence Sisyphus's absurd experience isn't that he pushes the rock up the hill only for it to fall back down, but that he does so even while also being conscious of that fact.
If this myth is tragic, that is because its hero is conscious. Where would his torture be, indeed, if at every step the hope of succeeding upheld him? The workman of today works everyday in his life at the same tasks, and his fate is no less absurd. But it is tragic only at the rare moments when it becomes conscious.
Much of the text is about resolutions to this contradiction in the human experience. Camus famously starts by framing the issue in terms of suicide, a sort of "quitting the game" response to the issue. He also examine leaps of faith, where you say that there actually is some underlying order one cannot understand, call it God, and use this to evade the absurd; finally he attempts to outline an attitude which he believes is a more honest grappling with the absurd.
All of that is to emphasize this tension, between wanting to know and not being able to know, that runs throughout the book. Camus addresses science because rational attempts to understand and parse the world are the most developed outgrowth of our impulse to understand. His question here is not whether science is useful or good or whatever -- I don't think he was any type of primitivist, for instance -- but whether science can provide a resolution by allowing us to grasp the nature of existence. So starting from a direct, sensorial experience of nature, Camus imagines someone breaking it down in scientific terms:
You describe it to me and you teach me to classify it. You enumerate its laws and in my thirst for knowledge I admit that they are true. You take apart its mechanism and my hope increases. At the final stage you teach me that this wondrous [20] and multicolored universe can be reduced to the atom and that the atom itself can be reduced to the electron. All this is good and I wait for you to continue.
When one studies physics or chemistry, one discovers many explanations for everyday phenomena -- indeed, that's pretty much why one would study physics or chemistry. As science continues, it has successfully pushed the boundary of understanding down further and further, to the atomic scale. (As a disclaimer -- I am a scientist -- this is a simplification of the actual nature of uncertainty in science, much of which today consists of how to put the pieces back together again so that the natural world can emerge from its constituent fundamentals. That's not really relevant here.)
But you tell me of an invisible planetary system in which electrons gravitate around a nucleus. You explain this world to me with an image. I realize then that you have been reduced to poetry: I shall never know. Have I the time to become indignant? You have already changed theories. So that science that was to teach me everything ends up in a hypothesis, that lucidity founders in metaphor, that uncertainty is resolved in a work of art. What need had I of so many efforts?
I don't know if you've ever studied quantum mechanics. It's a beautiful theory, but unfortunately the theoretical constructs hardly fit with our experience at all. We use terms like "the electron orbits the nucleus" as if it were a planetary system, but to actually deal with the system itself requires mathematical formalism pretty much entirely disjoint from how we experience the world. To Camus, who wants to achieve a bone-deep certainty of "this is how the world works, this is the order we all fit into" this isn't enough. He feels that science either retreats into metaphor or story, like a popular description, or it becomes a formal exercise in mathematics that is ultimately built up from presupposed axioms ("hypotheses that claim to teach me but are not sure"). There is no absolute truth here, and certainly nothing that can solve the problem of the absurd -- which is less about our ability to predict the results of scattering experiments than it is about our own human experience of wanting order in a disordered world.
I realize that if through science I can seize phenomena and enumerate them, I cannot, for all that, apprehend the world. Were I to trace its entire relief with my finger, I should not know any more.
