Spike Milligan summed up the human need for nostalgia quite succinctly, and it went something like - "With the present so troubling, and the future so uncertain, the past is a warm place that holds no fears at all". Looking back in time and turning over the leaves of the past is something that I am quite comfortable in doing. I do know some who shun such activities, that want to live in the present and not 'project' themselves back (or forward) in their minds.
To unearth events that have happened to us can stir many emotions - feelings of loss, a reminder of lessons learnt, a warm glow of joy, sadness that we are no longer the young carefree individual - but as we possess a memory it is strange to me that we don't all embrace it. Speaking for myself I am selective in what I revisit and am more than aware that those moments that I select are heavily lit by a rosy glow. They are worth more to me than any physical possession. I don't just embrace them, I celebrate them!
As for my memories via the world of nature, they come out to play on a regular basis. They are partly why I still go out into the field as I want to collect more of them. The need for rarity is massively lessened. When I cobbled together my 10 most cherished moments with nature, only one of them involved rarity. Such moments just happen. It doesn't need to be on top of a mountain or when stood before a raging seascape - you might be looking out of a window or washing the car.
And, going back to Spike's observation, because there is an element of the past being a known quantity, so the memories are of a time that we successfully negotiated and survived. They are shot through with comfort (and even the sadder ones can with the passing of time). We also think that there were more birds, more hedges, less uncertainty and, if the memories are old enough, of days when our cares were not clouded by 'grown-up' stuff.
I did have to laugh (ruefully) at a recent cartoon in Private Eye. An old woman is standing at a train station ticket office and says: "I'd like a return to simpler times please". In the current storm of Brexit, Trump and disappearing ice caps, I might just join her.