Answer: All the inanimate, vegetative, animal, and human life are gradually transformed into higher forms.
That is why the ancient fern and other plants became extinct, as did various kinds of animals. Even minerals have changed. According to researchers, you can tell how many million years old a particular rock is. Everything happens naturally.
The same holds true for the people. Just look at how different people living today are from those who lived a hundred or a thousand years ago. Even in their appearance, not to mention their level of consciousness.
If I were to teach Kabbalah today the way Aristotle and Plato wrote about it, claiming that the soul depends on how deeply a person breathes, I would be laughed at. Can you imagine what the great thinkers of the past wrote about?! With a deep inhalation and exhalation we fill our soul. And they really believed that is what the soul is.
Today, those great minds of their generation would look like silly boys if they remained on the same level because the constantly developing desire develops us. That is why we can not compare ourselves to other generations.
From the Kabbalah Lesson in Russian 3/19/17