"In the twinkling of an eye," is an idiom which has been used in a lot of literary works as well as quoted often. It means in a moment, in a second, and that things can happen quickly. Things can take place so fast that one might not even notice the change right away.
One place this quote is found is in a play by William Shakespeare. "The Merchant of Venice," Act ii. Sc. 2
"Well, if Fortune is a woman, she's a good woman for this guy. Father, come; I'll take my leave of the Jew in the twinkling of an eye. "
This quote can also be found in some translations of the Holy Bible.