Chapter 401: The Sphinx's Peak Ability.

He didn't know the full theory of it as it wasn't published but he understood that those Spiritual Eyes were the reason for the Witches having the sole ability to concoct potions.

It allowed them to examine the concoction at a microscopic level and use their mental energy to stop the concoction from turning bad.

If it wasn't for it, the mental energy would never be used at such a microscopic level.

Gadgets, equipment, and such, were all useless since even if one was able to see at a microscopic level, his metal energy would not shrink to that level.

Felix knew that without this step, the ingredients used wouldn't combine, absorb, or react to each other positively.

If he went and tried to concoct the potion, he wouldn't even know how it failed. That goes to everyone without those Spiritual Eyes.

That's why he was shocked by Lady Sphinx's ability to concoct.