Martin Heidegger said this quote

Everyone is the other and no one is himself.

~ Martin Heidegger

Thinking only begins at the point where we have come to know that Reason, glorified for centuries, is the most obstinate adversary of thinking.

~ Martin Heidegger

To clarify the existentiality of the Self, we take as our ‘natural’ point of departure Dasein’s everyday interpretation of the Self. In *saying* “*I*,” Dasein expresses itself about ‘itself’. It is not necessary that in doing so Dasein should make any utterance. With the ‘I’, this entity has itself in view. The content of this expression is regarded as something utterly simple. In each case, it just stands for me and nothing further. Also, this ‘I’, as something simple, is not an attribute of other Things; it is not *itself* a predicate, but the absolute ‘subject’. What is expressed and what is addressed in saying “I,” is always met as the same persisting something. The characteristics of ‘simplicity’, ‘substantiality’, and ‘personality’, which Kant, for instance, made the basis for his doctrine ‘of the paralogisms of pure reason’, arise from a genuine pre-phenomenological experience. The question remains whether that which we have experienced ontically in this way may be Interpreted ontologically with the help of the ‘categories’ mentioned.Kant, indeed, in strict conformity with the phenomenal content given in saying “I,” shows that the ontical theses about the soul-substance which have been inferred [*erschlossenen*] from these characteristics, are without justification. But in so doing, he merely rejects a wrong *ontical* explanation of the “I”; he has by no means achieved an *ontological* Interpretation of Selfhood, nor has he even obtained some assurance of it and made positive preparation for it. Kant makes a more rigorous attempt than his predecessors to keep hold of the phenomenal content of saying “I”; yet even though in theory he has denied that the ontical foundations of the ontology of the substantial apply to the “I,” he still slips back into *this same* inappropriate ontology. This will be shown more exactly, in order that we may establish what it means ontologically to take saying “I” as the starting point for the analysis of Selfhood. The Kantian analysis of the ‘I think’ is now to be added as an illustration, but only so far as is demanded for clarifying these problems.―from_Being and Time_. Translated by John Macquarrie & Edward Robinson, p. 366

~ Martin Heidegger

The ‘I’ is a bare consciousness, accompanying all concepts. In the ‘I’, ‘nothing more is represented than a transcendental subject of thoughts’. ‘Consciousness in itself (is) not so much a representation…as it is a form of representation in general.’ The ‘I think’ is ‘the form of apperception, which clings to every experience and precedes it.’Kant grasps the phenomenal content of the ‘I’ correctly in the expression ‘I think’, or—if one also pays heed to including the ‘practical person’ when one speaks of ‘intelligence’—in the expression ‘I take action’. In Kant’s sense we must take saying “I” as saying “I think.” Kant tries to establish the phenomenal content of the “I” as *res cogitans*. If in doing so he calls this “I” a ‘logical subject’, that does not mean that the “I” in general is a concept obtained merely by way of logic. The “I” is rather the subject of logical behavior, of binding together. ‘I think’ means ‘I bind together’. All binding together is an ‘*I* bind together’. In any taking-together or relating, the “I” always underlies—the ὑποκείμενον [hypokeimenon; subjectum; subject]. The *subjectum* is therefore ‘consciousness in itself’, not a representation but rather the ‘form’ of representation. That is to say, the “I think” is not something represented, but the formal structure of representing as such, and this formal structure alone makes it possible for anything to have been represented. When we speak of the “form” of representation, we have in view neither a framework nor a universal concept, but that which, as εἶδος [eidos], makes every representing and everything represented be what it is. If the “I” is understood as the form of representation, this amounts to saying that it is the ‘logical subject’.Kant’s analysis has two positive aspects. For one thing, he sees the impossibility of ontically reducing the “I” to a substance; for another thing, he holds fast to the “I” as ‘I think’. Nevertheless, he takes this “I” as subject again, and he does so in a sense which is ontologically inappropriate. For the ontological concept of the subject *characterizes not the Selfhood of the “I” qua Self, but the self-sameness and steadiness of something that is always present-at-hand*. To define the “I” ontologically as “*subject*” means to regard it as something always present-at-hand. The Being of the “I” is understood as the Reality of the *res cogitans*.―from_Being and Time_. Translated by John Macquarrie & Edward Robinson, pp. 366-367

~ Martin Heidegger