One would not take it upon himself to consider his place before making his greeting. Locking eyes with a stranger passing by, the brief moment of mutual acknowledgement between subway seat occupants, or perhaps encountering acquaintances in your Wednesday afternoon class. The mind does not wander the gilded halls of substantial conversation in these situations, as it would be naive and arrogant to expect such reciprocations from each and every individual that one comes across on a daily basis. The oft forgotten fact that one exists with others, a foundational reality of our society and indeed our disposition as social animals, must be consulted in order to justify our omission of our place. So then what comes out of our mouth which we so confidently call a greeting? "Hello". With a slight chance of "Good Day", or perhaps a "How Are You". In any case, these variants carry nary more meaning than Hello. Worlds apart from a tacit and intentional confirmation of each other's existence, these "greetings" fulfill the simple objective of denying the progression of substance.
Substance is never present. It is a state in which the present must transfer through in order to attain purpose. Standing still and not running on the track, while most likely wholly counter to one's intended goals for that day out in the field, lacks substance. The dynamism of moving one's legs and pounding the ground, feeling the wind rush past the ears, and turning acutely aware of all moving compartments of the body, is at once an inevitable consequence of the act of running, as it is the substance of the act itself. This transitional nature, going from a static constancy to an ephemerally recursive affirmation of one's present state, defines the substantiality of one's being. From one moment to the next, the body flows through the real aspect of running, and the purpose of this specific action is born. The present must flow through the never present substance in order for its purpose to make itself known.
The coded action of a "Hello!" lacks such dynamism as it is contingent on its perpetrator omitting the intent and action of shifting their state. Perhaps in a humble room one calls their own, with an interlocutor one desires, and an occasion fancied by both parties of this meeting, can a shift in state occur within the greeted friends, but alas. On the familiar morning commute, with no more than a glass of water and a cup of coffee in the system, this unquestionable tampering of one's entropic state does not entice. "Hello", one would transmit, perhaps with a strong intent to make it be known even among others within earshot, regardless of whether they're the intended targets of such words or not, and consider an obligation met. Not realizing that not a single aspect of yourself has moved.