You can find bacteria everywhere. They're invisible to us. I've never seen a bacterium, except under a microscope. They're so small, we don't see them, but they are everywhere.
The more often we see the things around us - even the beautiful and wonderful things - the more they become invisible to us. That is why we often take for granted the beauty of this world: the flowers, the trees, the birds, the clouds - even those we love. Because we see things so often, we see them less and less.
A common measure of poverty is how much money you have in relation to other people - that is useful as far as it goes, but that excludes the case of, say, a hunter in the rainforest who has no money but is not poor. And there can be a number of people with money but who can consider themselves unwanted or invisible or estranged from society.
When our spelling is perfect, it's invisible. But when it's flawed, it prompts strong negative associations.
Love is a force more formidable than any other. It is invisible - it cannot be seen or measured, yet it is powerful enough to transform you in a moment, and offer you more joy than any material possession could.