>>>BTW, in the UK we call them "Blind Dogs". It may sound a bit strange to you but, otoh, what the heck else is an eye for but for seeing
>>
>>Eyelet, grown up?
>
>But i said, what's it for, nor what does it spring from.

Ah, so it's the purpose principle... so an eyelet is a proto-microscope then, for seeing small things.