On Sunday's Westworld, Bernard had an encounter with Maeve that sent his robo-mind spinning. So, he forced Ford to access all of his memories to meet all of the host's maker, Arnold.
Bernard went to his very first memory, the tragic death of his son. That was directly followed by Ford waking Bernard in a lab. Ford explained, "You are the perfect instrument, the ideal partner, the way any tool partners with the hand that wields it. Together, we're going to do great things. After such a long absence, it's good to have you back."
Bernard realized then that he was Arnold. Technically he's a newer host-version of Arnold but carefully crafted to the smallest detail.
This revelation called into question Bernards relationship with the hosts, especially the ones that have been awakening. It also asks the question, "Have we seen the original Arnold?"
However, this wasn't the first time that Ford's had this conversation with Bernard and engineered a backdoor failsafe that forced Bernard to committed host-suicide as Ford walked away from his familiar creation.