The only limit is the one you set for yourself.
The teacher who is indeed wise does not bid you to enter the house of his wisdom but rather leads you to the threshold of your own mind.
The problem with defending the purity of the English language is that English is about as pure as a cribhouse whore. We don't just borrow words; on occasion, English has pursued other languages down alleyways to beat them unconscious and rifle their pockets for new vocabulary.
We don't just extract oil; we extract potential for economic growth and development.