Following on from this...
It could be 'age', though I doubt it, because I know far too many people who would also qualify as the same 'age' as I, but who wouldn't for a moment have the same kinds of...let me call it 'sense' of something that is difficult to out into words. Besides, being of a contemplative inclination—to the point of exasperating people sometimes when they really would like things to be light and fluffy, but I refuse to oblige—such thoughts are less likely to be brought about by the mere fact of getting older and much more by what you might call 'life contingency'.
So, here's one of those things; maybe the biggest one.
Have you ever some across one or more of those people who, while being in quite OK circumstances and having nothing concrete to complain about—short of the usual usual, which is always present, no matter how 'OK' one's life may be—nonetheless complain about the 'emptiness' of their lives; it's lack of 'meaning' and/or the absence of 'personal fulfillment'; things just not going 'right' or along some self-devised or conceived 'plan' or 'path'; and so on?
Their plaint is often wrapped up in the statement that there's just got to be more to 'existence' than...well, 'mere existence'. Getting up in the morning and going to bed at night. Bob Seger in his song 'The Ring' wrapped up that sense of there just not being enough, of something missing in those two lines:
...Another day comes to and end Another day just ends...
BTW, I am a kind of fan of Bob Seger's as well. Here's a gratuitous insert of a music video of his, just to break up the philosophizing.
This plaint about the unsatisfactory nature of 'mere existence' comes about because...well, just because we exist. We also take 'existence' for granted. We can't help it—again, just because we do exist. Non-existence is actually, in the immortal words of Vincini, 'inconceivable!'
And I don't just mean our existence as human beings, but the existence of any-thing. EUL. Of course, our own personal existence, as 'being alive', is the predominant and maybe most awe-inspiring aspect of this, given that at one stage each of us really didn't exist, then came into existence, and subsequently will, at some stage, cease to exist—as a creature aware of its own existence anyway.
That, when you really start thinking about it, is heady stuff! So dazzling and overwhelming in its plain glorious reasonlessness that people invented ways to make it appear reasonable; an action that in itself lacks any foundation in 'reason', excepting a circular snake-bites-its-tail kind of way. Making it seem like it were in any way 'sensible', from some higher point-of-view, that there is anything at all. Ever. As if the very notion of what 'makes sense', of 'reason' and 'logic' and all that, weren't actually only possible, or even 'created' by, if you will, the basically not 'sensical' at all of 'existence' itself.
When you go down that path of thought you'll discover some truly amazing things, the most breathtaking of which is the utter, complete, all-enveloping and glorious absurdity of it all. And, far from staring into an 'existential void' that needs to be filled up with some silly God so that it isn't quite as 'void', what you're really looking at it yourself—because by looking you are existence itself regarding itself. The Absurd appreciating its own Absurdity and saying "Whoa!"
Oddly enough, my daughter Aynia, quite by chance, just happened across some evidence that people react very strangely to the un-reflected-upon but nonetheless 'sensed' notions outlined above. And this here is definitely indicative of a need to be more aware of what goes on in one's head when dealing with the great LUE.
Or maybe it really is just evolution in action.