Final answer:
Plato and Spinoza have explored the concept of existing under the aspect of eternity.
Step-by-step explanation:
The question of whether we exist under the aspect of eternity has been explored by philosophers such as Plato and Spinoza. Plato believed that the changing world we see is a mere shadow of a higher, truer reality that is eternal and unchanging. This otherworldly reality is the ultimate reality, and the seat of all truth, beauty, justice, and wisdom.
Spinoza, on the other hand, coined the phrase 'sub specie aeternitatis,' which means seeing things from the perspective of eternity. While their focus was primarily on God and the world, not on ourselves, these philosophers provide a framework for considering the concept of existence under the aspect of eternity.