A man chooses, a slave obeys

"A man chooses. A slave obeys."

“A man has a choice... I chose the impossible.”

― Andrew Ryan

'Choice' is one of the major themes of BioShock, and is inherent in Andrew Ryan's personal motto. The theme of self-determination and the question of destiny in the game is embodied by this phrase. During the game, the player, Jack, is given many choices, both tactically and morally, but his actions turn out to be illusory: his will had been controlled and driven by Frank Fontaine, under the guise of Atlas, via the phrase he'd been conditioned to obey, "Would you kindly..."

Ryan, once he identified that Jack was actually his illegitimate son, first openly controlled him with the code phrase, forcing him to obey pet commands to convince him of how powerless he really was. Andrew Ryan then used this phrase to have Jack kill him.

“Stop, would you kindly? (Jack reacts instantly, and obeys the command involuntarily) 'Would you kindly'... Powerful phrase. Familiar phrase? (Jack experiences a cascade of memories of Atlas including the phrase in his "suggestions") Sit, would you kindly? (Jack obeys) Stand, would you kindly? (Jack obeys) Run! Stop! Turn. (Jack obeys) A man chooses, a slave obeys. (Ryan hands Jack his golf club) Kill! (Jack obeys, striking him with the club) A man chooses! (Jack strikes again) A slave obeys! (Jack strikes again) OBEY! (Jack kills Ryan with a final, deadly blow) ”

― Andrew Ryan

Ryan did this not as an intentional suicide, but to try and break the mind control.

Unable to stop, Jack was forced to acknowledge that he never had a choice, even the "plane crash" that sent him to Rapture was due to Jack hijacking the plane and deliberately crashing it at the lighthouse.

However, Jack's complete lack of choice is ultimately proven false as one act that Jack does have a choice in - saving/harvesting the Little Sisters - defines who he is: the kind savior of Little Sisters who gives them a chance at normal happy lives (something Jack was denied since birth) or the bloodthirsty, power-hungry king of Rapture, not unlike both of his "fathers" Andrew Ryan and Frank Fontaine.