The shift from spring to summer is subtle but it's still real. You have to look for it. You have to notice the rise in temperatures and the sun's more direct rays. The gardens go from fresh and green to full production and quickly change to browning vines and withered stalks.
Writers often use the seasons as a metaphor for life. Our seasons are joyous and sad as we enter one and leave the other. And yet, it represents the way we are going, the progress we are making. I can't be too depressed that I have accomplished things in this stage or this season. Some of them I get to continue, but for some there is no need to redo. For them the memory is enough.
For some of my accomplishments or successes, other people take up the baton and the race continues. My children teach their children, and their seasons and lives take up when mine is leaving off. It never seems to get back to the beginning again; the seasons and the cycles roll on in a spiral or a looping progression of advancement. That's right and, yet, the changing of a season carries a sadness that is undefinable.
The final verse of Robert Frost's poem "Reluctance" says it well.
Ah, when to the heart of man
Was it ever less than a treason
To go with the drift of things,
To yield with a grace to reason,
And bow and accept the end
Of a love or a season.