The basic Laws of Thermodynamics (or "thermogoddamits", as my father used to call them while studying for his PhD in Chemical Engineering)...
Neither matter nor energy arise out of nothing. In all the Cosmos, there is what there is (probably). Matter and energy transform, traveling over space and time, from body to body, clustering, dispersing, in a giant web of interconnection, from the Big Bang on.
There is so much vast empty space between our solar system and other clusters of matter and energy that in practical terms, the matter and energy in our solar system are what our solar system has to deal with, nothing more. The preceding statement is an oversimplification and technically inaccurate, but close enough to be workable.
The Sun, that great nuclear reactor at the center of our solar system, constantly bombards its surrounding planets, including Earth, our home, with energy in the form of heat and light. Some of this energy is reflected off our atmosphere into space, some is absorbed and put into use here on Earth, and eventually radiated out from our planet into space, in a state of dynamic equilibrium.
Earth gets some inputs of matter from outside itself -- meteors, space dust and such -- but this input is not enough to be a major source of renewal of the matter on Earth. We are a finite planet, and we must rely on the matter already here for ongoing renewal of all the forms on Earth, including our own bodies, the soil, the water, and so much more.
(If we ever do receive an input of matter from outside Earth that is big enough to provide significant additional matter to deal with, the collision will be so destructive to current forms as to destroy human and most other life, and transform our planet, so we needn't bother with that possibility here.)
Bottom line: the Earth is finite. We've got what we've got, so we must take care not to trash it.
Here on Earth as everywhere else, all matter and energy are constantly transforming, traveling from place to place over time, from body to body, clustering, dispersing, in a planet-wide web of interconnection that began with the formation of this planet and will continue until it is finally obliterated in the ultimate violent death of our Sun (or perhaps sooner, in a collision with a sufficiently large asteroid.)
"Economy" is ultimately that interchange of matter and energy. The notion of infinite, unending growth, economically and otherwise, has always been an especially foolish myth.
An interchange of matter and energy, in dynamic equilibrium, has evolved on Earth over the millennia. The nature of the dynamic equilibrium changed significantly over time. Currently, it supports human life as part of a vast, complex, interconnected web of many, many life forms and so-called non-living forms such as soil, air, water, rocks...
The dynamic equilibrium of matter and energy on Earth has not always been such as to support human life, and there is no guarantee that it will remain so. That is an important point to keep in mind. We humans are almost certainly not so powerful as to be able to destroy all life on Earth (life can be incredibly tough, and has already adapted to many extremes.) But we can screw the current equilibrium up to the point that Earth wipes us out as a species (along with a huge number of other species -- collateral damage.)
After all, the vast majority of species that have ever evolved on this planet have gone extinct -- extinction is the most common outcome of evolution.
As for me, I love being alive. For all that human beings can be incredibly destructive, foolish, and short-sighted (particularly regarding our relationship with our planet and its many inhabitants) we also have some truly wonderful and unique qualities and potentials that I believe to be valuable in the mix. I would like for our Earth to continue to be able to support human life and as many as possible of the other current life forms as well, in a context of abundance and beauty. Which means that we human beings, especially those living in or aspiring to an industrialized lifestyle, have to change our ways of living on Earth.
Fortunately (if challengingly) we will be forced to do so.