I leave you the best phrases of Parmenides (530 BC-515 BC), probably the Greek philosopher whose philosophy is best preserved today. All that is preserved of his writings is from a philosophical poem divided into two parts: The way of truth and The way of the opinions of mortals.
You may also be interested in these phrases of Anaximander or these of famous philosophers.
-The same is every starting point for me, because I have to return to it.
-Give me the power to produce fever and I will cure all diseases.
-The change is an illusion.
-Observe things that, although distant, are still present in the mind.
-Everything is of the nature of nothing.
-Let reason decide alone.
-You cannot recognize non-being, you cannot talk about it, because thought and being are the same thing.
-The steeds take me as far as my mind can.
-The same remains in the same, and rests in itself.
-The reason will end up being right.
-War is the art of destroying men, politics is the art of deceiving them.
-Music that does not describe something is nothing more than noise.
-Everything there is has always existed. Nothing can come from nothing. And something that exists cannot be converted into anything.
-There is a missing story, a path, that is. And on this path there are many signs in which being is not created and is imperishable, whole, unique, firm and complete.
-You must learn all things, the unshakable heart of persuasive truth and the opinions of mortals in which there is no guarantee.
-Therefore, all those things are nothing more than the names that mortals have given them, believing them to be true.
-Well, the same thing is what can be thought and can be.
-Well, you will never tame what it is not. But you, from this search path, remove the thought that you think.
-Don't let habit be born from experience, force yourself on this path, aiming your eyes and ears aimlessly, but judging with reason.
-The universe, for those who knew how to cover it from a single point of view, would not be, if it were allowed to say so, more than a single fact and a great truth.
-We can only talk and think about what exists. And what exists has not been created and is imperishable because it is a whole, complete and does not change. It was not or should not be different than it is now, all at once, one and continuous.
-Well, then, I'm going to tell you (and pay your attention to the story that you hear me)
the only search paths that can be conceived:
the one, the one that is and it is not possible that it is not,
is a route of persuasion, because it accompanies the truth;
the other, that it is not and that it must not be,
this I assure you is a totally inscrutable path.
-And only the mention of one way
remains; the one that is. And in it there are signs
in abundance; that it, as it is, is unbegotten and imperishable,
whole, unique, immutable and complete.
-The mares that carry me led me to the goal of my heart, since in their career they transported me to the famous path of the deity that, alone, leads the man initiated into knowledge through everything. I was taken there, because the very intelligent mares who pull my cart took me there, while some maidens showed me the way.
-A single possibility of talking about a path remains: what it is. In this there are many signs that what is has not been generated and is imperishable, because it is of intact members, intrepid and without end. It never was, nor will it ever be, since it is, now, all together, one, continuous. Because what origin will you look for? How, where would it have taken off? Of what it is not, I will not let you say it or think it, because it is not possible to say or think that it is not. And what necessity would have made him be born later rather than before, taking the principle of what nothing is? Thus, it is necessary that it be totally, or that it not be.
-Nor never will the force of faith allow something to be generated by its side from what it is not. Therefore, neither to be generated nor to perish, Justice allows him, releasing his chains, but rather has him subject.
-Nor is it divisible, since it is all the same, nor is there more anywhere, which would prevent it from being continuous, nor less, but everything is full of what it is. This is why everything is continuous: because what is touches what is.
-The same is what can be thought and that for which thought exists that is thought, because without what it is, and at the point at which it is expressed, you will not find thinking. Because nothing different neither is, nor will be, next to what is; at least Fate bound him to be whole and immobile.