Did Jesus Offer Secret Teaching to His Closest Disciples?

Gospel of thomas is thought to have been written toward the end of the first century or during the second, circa 90 to one forty a d. The gospel of mark says explicit that jesus did offer secret teaching to his closest disciples. But does it? Even if he did, and the example of other first century text makes this seem likely, we cannot assume that this text accurately transcribes what jesus actually taught. We simply have no way to know.