Answer: We can develop our sensitivity only under the influence of the Upper Light; call it the Creator or the Surrounding Light. No force in our world can help us do that. The Upper Light created us and gave birth to us.
It develops us, and we can spur its impact on us at any time, but before we do that, we must understand how to do it. The wisdom of Kabbalah teaches us how.
From the Kabbalah Lesson in Russian 8/21/16