"Du wirst das an dir selbst gewiß noch oft beobachten können" from Der Verschollene by Kafka

Question

This post is on an dir selbst as highlighted in this passage from chapter 'Der Fall Robinson' of Amerika (Der Verschollene) by Frankz Kafka. In this passage, Karl Rossmann is being cashiered at a hotel, and its Head Porter is addressing him.

»Es ist möglich«, fügte er [der Oberportier] hinzu und unterhielt sich dabei königlich, »daß du [Karl Rossmann] bei einem anderen Ausgang unbemerkt hinausgekommen wärest, denn du standest mir natürlich nicht dafür, besondere Anweisungen deinetwegen ergehen zu lassen. Aber da du nun einmal hier bist, will ich dich genießen. Im übrigen habe ich nicht daran gezweifelt, daß du das Rendezvous, das wir uns beim Haupttor gegeben hatten, auch einhalten wirst, denn das ist eine Regel, daß der Freche und der Unfolgsame gerade dort und dann mit seinen Lastern aufhört, wo es ihm schadet. Du wirst das an dir selbst gewiß noch oft beobachten können.«

QUESTION

Does it mean:

(a) in yourself: I.e. Karl is observing himself. The tendency to stop being vicious only out of self-interest (only when it hurts him) is in Karl. Karl will come to see that in himself often enough.

(b) on your own: I.e. Karl uses his own power of observation. The tendency is general though it may be in him too. Karl will come to see that for himself (and not have to take the Head Porter's word for it).

ADDENDUM

If the distinction between (a) and (b) is not clear (as an answer suggests), please consider these examples.

In yourself: You come of a line of soldiers, but want to be an artist. Your father says you would soon see the warrior in yourself. This expression locates soldier-likeness in you. You are soldier-like.

On your own: Your father says that the world only respects power, and you disagree. He says you will come to see the truth on your own (or for yourself, i.e. without anyone else having to tell you). Here, the expression is not locating respect for power anywhere in particular. The expression describes how you are going to see it. You may or may not respect power.

The question is, in which of the two situations you would use an dir selbst.

Answer 1

It's closer to (a). However, the preposition an in connection with verbs of discerning (sehen, beobachten, feststellen, …) has evolved beyond a merely spatial meaning (where?) to denoting a source of knowledge.

Er hat Schmerzen. Man sieht das an der Art, wie er sich bewegt.
He is in pain. You can tell from the way he moves.

Smartphones lenken ab. Das sehe ich an meinen Schülern.
Smartphones are a distraction. I can tell that from looking at my students.

Das siehst du doch an dir selbst.
You can tell by looking at yourself.

An ihm kann man sehen, welche Folgen Drogenkonsum hat.
You can tell what the consequences of taking drugs are by looking at him.

English and German in might carry that meaning as well, but in my opinion they focus more on the relationship between part and whole. In your example of seeing the warrior in yourself, this is understood as a part that has been hidden.

The meaning on your own in the example you quoted comes from du (i.e. Karl) being the subject.

Also I think you misinterpreted the following part.

[…] daß der Freche und der Unfolgsame gerade dort und dann mit seinen Lastern aufhört, wo es ihm schadet.

This means that Karl will stop being disobedient only when stopping being disobedient, i.e. becoming obedient, will hurt him. (A beautiful example of irony.)

Answer 2

The senior concierge (Oberportier) is saying to Karl:

... das ist eine Regel, daß der Freche und der Unfolgsame gerade dort und dann mit seinen Lastern aufhört, wo es ihm schadet.

... it is a rule, that the impertinent and the disobedient will stopp his bad habits exactly when it begins to harm himself.

The next sentence form the senior concierge is:

Du wirst das an dir selbst gewiß noch oft beobachten können.

My English is not good enough to give you a correct translation. (I can't see how they mean different things.) But I can tell you what the sentence means:

It means, that Karl now has not yet reached the point where his bad habits do harm him. But the senior concierge makes the prophecy, that some day Karl will reach the point where his bad habits might harm him, and then (so says the senior concierge) Karl will stop his bad habits at exactly this point, and Karl will be able to realize that he is changing his own behavior.