When it comes to gashmius we can say, יגעת ולא מצאת תאמין...

If someone with a brilliant mind tells you that he spent his entire life trying to understand the physics of the universe, yet the deeper he goes the more he doesn't understand, that is a person I would believe. Why? Because that's exactly how it is with the Torah. And the universe and the Torah have the same author.

But in ruchniyus, יגעת ולא מצאת אל תאמין. Why?Because, as the Kotzker once said, “I wouldn’t want to serve a G-d I understand”. Therefore, since we’re not looking for understanding, we’re looking davka NOT to understand and serve Hashem through Emunah, יגעת ולא מצאת אל תאמין. Because the יגיע itself is emunah. And therefore, the actual יגיע itself is already a bechina of מצאת.