A way that is open we call free. Entrance and passage are granted. These show themselves as spaciousness. What can be traversed is known to us as the spaciousness of spaces, as their dimensional essence, an essence we also ascribe to time—by speaking of a "span of time" for instance. This represents what we presumably first encounter in naming the "open": an unclosed and unoccupied extension prepared for the reception and distribution of objects.
Yet the open in the sense of the essence of ἀλήθεια does not mean either space or time as usually intended, nor their unity, space-time {Zeit-Raum}, because all that already had to borrow its openness from the openness holding sway in the essence of disclosedness. Similarly, everywhere that something is "free of ..." in the sense of "exempt from ...," or is "free for ..." in the sense of "ready to ...," a freedom already comes to presence out of the freedom that first releases even space-time {Zeit-Raum} as an "open," traversable, extension and spread. The "free of" and the "free for" already require a clearing in which a detachment and a donation constitute a more original freedom that cannot be grounded on the freedom of human comportment.
Hence we will never arrive at the open, as the essence of aletheia, simply by stretching the open in the sense of the "extended" or in the sense of the "free" as commonly understood, stretching it into a gigantic container encompassing everything. Strictly speaking, the essence of the open reveals itself only to a thinking that attempts to think Being itself in the way that it is presaged to our destiny in the history of the West as what is to be thought in the name and essence of ἀλήθεια. Every person in history knows Being immediately, though without acknowledging it as such. But as undeniable as is the immediacy of this knowledge of Being, that is also how rarely the thinking of Being succeeds or even commences. It is not that this thinking is difficult and would require special arrangements in order to be carried out. If we may speak of a difficulty here, it consists in the fact that to think Being is very simple, but that the simple is for us the most arduous.
To think Being does not require a solemn approach and the pretension of arcane erudition, nor the display of rare and exceptional states as in mystical raptures, reveries, and swoonings. All that is needed is simple wakefulness in the proximity of any random unobtrusive being, an awakening that all of a sudden sees that the being "is."
The awakening for this "it is" of a being, and above all the remaining awake for the "it is," and the watching over the clearing of beings—that constitutes the essence of essential thinking. The "it is" of beings, Being, shows itself, if it does show itself, in each case only "suddenly"—in Greek ἐξαίφνης, i.e., ἐξαίφνης, the way that something irrupts into appearance, from non-appearance. To this essentially unmediated and immediate irruption of Being into beings, which in turn only then appear