first quote says that the fact that i exist "for myself" is ontologically prior to any knowledge i can have: existence precedes essence. the second that recognizing 'being' is the same as me being for myself: that something like 'the meaning of being' reveals my existence that precedes essence. i just don't know what ontologically prior rather than ontically so (that the for itself is composed of no essence) could really mean though (and it seems to me we do have an ontic essence of sorts). it could just be sartre saying that 'the meaning of being' is the basic question to ask myself

Based on the other question, I assume B&N is Sartre's Being and Nothingness.

Yes you are correct in that assumption.

Sartre is compares his philosophy with Idealism. For the latter, consciousness is the measure of being, and this is knowledge. For Sartre, consciousness, which is pure nothing, is the establishment of the presence of being, because for-itself appears in the middle of being beyond it, as what is not. For-itself rejects itself because it is no more than nothing, which makes being possible to appear, show itself through as articulated, in the form of knowledge: "The For-itself by its self-negation becomes the affirmation of (about) the In-itself".

"For-itself adds nothing to the In-itself except the very fact that there is [exists] In-itself; that is, the affirmative negation". Here Sartre says that consciousness, by making itself aloof, articulates the masses of Being into the being which exists, is present (knowable). Knowledge is not our info of the there thing, it is the thing itself having been established, affirmed.

What I am confused about in the second passage is that he seems to be contradicting himself in the very same sentence.

Truth be told, it is also not really clear to me why Sartre objects the idealist conception of Knowledge in general.

In the second passage, "nothing" means cheap, not "nothingness". It translates like: it is very easy, like a tautology, to say that being 'exists', and yet your saying brings a radical upheavel with being, since being exists (= is as a fact of "something)" only due to for-itself (the consciensness) which itself is nothing.

Sartre hated the idea that ideas of things are the internal content, copies of outer things, or that they are prototypes which become outer real things. For him, the perceived tree as perceived one is real and is out there. This is a form of phenomenologic stance which is clear of both "idealism" and "realism".

I don't understand how it affects a 'total metamorphosis' that state is what bugs me here. What is the metamorphosis that he is referring to and why does it occur? Your reply is not quite clear on this.

Also he seems to contradict himself for he says earlier on that the being of the for-itself is knowledge of being and that he says that it has identity with to for-itself... but then he says later on that knowledge is reabsorbed in being(in itself) latter on... wha?? Oh yes and just to add he says that knowledge is confused with the ekstatic being of the for-itself, it seems to be a contradiction!

I said in my comment, that metamorphosis with being (the upheavel) is that Being (which is all in itself so deeply and sluggishly that it cannot be a fact of something articulated - see the 1st section of BaN) suddenly becomes a fact of a particular being at hand, something which is real.

So it is not cheap... also is the metamorphosis is referring to the For-itself because the for-itself is a modification of the in-itself?

He isn't not saying that by saying there is being, one creates the for-itself.

for-itself xannot be created, it is unsubstantial, it is the pure negation of being.

He seems to be conceding with idealism at the start of the section by saying that Knowledge is subjective.

He isn't saying that by saying that there is being one is referring to the for-itself. Is this what the affecting means?

@Deepthinker101 This is how socratic discussions start :-)

So what he seems to be saying in his objection of idealism is that knowledge of being = being and the for-itself = being therefore for itself = knowledge of being, something doesn't seem convincing here..