There’s a very old rhyme variations of which have been circulating in gardening circles since at least the mid-19th century, probably much earlier in fact. And it teaches a good gardening lesson. My father taught it to me when I was a kid. There are dozens of variants, but this is the one I learned:
Four seeds in a row:
One for the mouse,
One for the crow,
One to rot,
And one to grow.
Other versions mention blackbirds, rooks, cutworms, withering, etc.
The reference is, of course, to sowing seeds and the importance of always sowing more than you actually need because, inevitably, you always lose a few.
When I sow indoors, I usually sow 3 seeds for every plant I actually want. If more do grow than I need, I simply pinch off the excess ones at the base. If you’re really good with seeds, you could try sowing two rather than three.
Outdoors, where so much more can go wrong, I really do sow 4 seeds for every plant, like in the rhyme. Again, should they all come up, I thin out the extras.
I usually wait until there are 4 or more true leaves before I thin… by then any cutworms in the vicinity have had time to strike and I’ve eliminated them.