The Diamond Sutra is also called the Vajra Prajna Paramita Sutra which means the Perfection of Indestructible Wisdom Sutra.
Vajra is an indestructible material like Diamond.
So why is a Sutra about indestructibility talking about things like drops of dew which are as ephemeral as they come?
It’s because normally we attach to all these ephemeral, transient things in our lives that we want and expect to be permanent – and when they disappear from our grasp like the evaporating drops, we suffer because we still want these transient things to be around for us to enjoy. But it is not the nature of the created things in this world to be permanent – all created things, all things that are born, all things that have a beginning – are of the nature to be constantly changing – and so will eventually end, die off and be separated from us.
So the Diamond Sutra here is telling us to let go of these transient, fickle, insubstantial things in our lives – see through them. And this way we can then begin to understand our non-transient, indestructible Vajra nature, our real nature – our Buddha Nature.
How do we know this? Because the Diamond Sutra limits this contemplation only to conditioned phenomena – not the unconditioned.
Further, how can you gain indestructibility from things that are transient and die off on you? You can’t! Hence why you’ve got to see through and let go of all these transient things so that what is not transient can be glimpsed.
So it says at the end of the Diamond Sutra (I’m paraphrasing the key meanings from the Sutra rather than just relying on 1 translation):
This is how we should contemplate things in this fleeting world:
Like dreams, bubbles, illusions, shadows, like a falling star, like dew drops and a lightning flash.
All conditioned phenomena should be contemplated thus.