Heidegger says, “Every thinker thinks one only thought,” and again, “The thinker needs one thought only, and for the thinker the difficulty is to hold fast to this one only thought as the one and only thing that he must think.”
This idea of the one only thought reminds me of Kierkegaard when he says that “Purity of heart is to will one thing.” Of course, it would not do to conflate Kierkegaard with Heidegger here, and it would be very hasty indeed to assume that willing one thing and thinking one thing are necessarily related, but I am tempted nevertheless to say that thinking one thing might require a certain purity also, not a purity of heart perhaps, because the heart’s purpose is to will, but a purity of mind. If purity of heart is to will one thing, then perhaps purity of mind is to think one thing. Perhaps holding fast to the one only thought is just such a purity.
Would it be too daring to suggest now, as I deliberately refrained from suggesting just a paragraph ago, that the one only thing to be willed by the pure heart and the one only thing to be thought by the pure mind are one and the same? This is, I think, an audacity that would remain unjustified even after much patient work. Even so, I will say it, unjustified as it may be, and I will say also, though it dares much more, that a purity of heart and a purity of mind require each other to become fully what they should be.
Yet, how does the thinker come to think this one only thing, come to encounter it, come to recognize it? Will it consent to be named? If I was to give it a name, if I was to call to it by name, to call it love, perhaps, or to call it hospitality, or to call it justice, or even, surely in a moment of great rashness, to call it God, how much would these names, one or another, deform the one only thought that I must hold fast, the one only thought that these names try but fail to name? Is this why Heidegger goes on to say that the thinker must keep saying the one only thought in the manner that befits it, in a manner that lets the thinker be claimed by it? Is it that the thinker must keep saying, again and again, in whatever ways seem best, this one only thing that is always the same thing? Is it that this one only thing must claim the thinker precisely because the thinker can never claim the one only thing?
How then does the thinker hold fast to this one only thought that must be thought, and must be said, but can never be claimed, like a desire, a discipline, a lust, a commandment, a will, a need, a perseverance? How is it that we are to think this one only thing?