This question on whether Darth Sidious knew the secret of cheating death inspired me to ask. The consensus on that question is that Darth Sidious did not know how to cheat death, and that his master's secret died when Sidious killed him.

Why didn't he wait until after he learned the secret of cheating death before killing his master?

Did he believe he really knew, only to discover he didn't actually know? Implying that he slew his master too soon. (Side note: if a Sith Lord learns to live forever, they really don't need an apprentice to continue the Sith order through the Rule of Two.)

Or was everything Palpatine told Anakin about a Sith Lord powerful enough to save the ones he loved from death all just a lie to lure Anakin to the dark side?

Please provide answers from canon sources.


3 Answers 3


The information we have about Darth Plagueis from canon is very limited and comes from only two sources: Episode III and the canon novel Tarkin.

The most relevant facts are that Plagueis was Sidious' master until some time after Sidious became the senator from Naboo:

[Sidious and Tarkin] had met several years after Sidious -- still an apprentice of Darth Plagueis at the time -- had been appointed Naboo’s representative to the Republic Senate.

Tarkin, p. 102

We don't know exactly when Plagueis was murdered -- he may or may not have been alive during the events of Episode I.

We also know that Plagueis disdained "trivial" political matters and did not foresee that Sidious would rise to become Emperor:

The Emperor spent a long moment studying Ison and Rancit, stretching out with his powers to discern alignments, configurations, some syzygy of events. Then his thoughts turned to Vader and Tarkin. He appreciated how well they were working together, but he began to wonder if they were perhaps too close to the details of the dissidents’ scheme to recognize their ultimate objective. One needed to have a safe remove, as he felt he had, gazing into the 3-D representation of the galaxy he had made his own. How Plagueis would have mocked him for allowing himself to become personally involved in such a seemingly trivial matter; but then his Master had never foreseen that his onetime apprentice would become Emperor.

p. 103

From these two pieces of information we can make an educated guess: Plagueis and Sidious apparently had a disagreement about how to proceed with their attack on the Jedi/Republic; this disagreement precipitated a conflict between them which Sidious won, but Sidious was unable to learn how to cheat death from Plagueis (assuming Plagueis had learned it) before the murder. Sidious probably decided that he needed to go his own way, so he killed Plagueis in surprise -- this would be consistent with Sidious' story to Anakin about Plagueis being killed in his sleep.

We do know from canon that Plagueis and Sidious apparently tried to learn the final secrets of the dark side of the Force (such as cheating death), but it's not clear if Plagueis ever figured it out:

Save for Sidious, no sentient being in close to five thousand years had set foot in the shrine [under the former Jedi Temple]. The room’s excavation and restoration had been carried out by machines under the supervision of 11-4D. Even Vader was unaware of the shrine’s existence. But it was here that they would one day work together the way Sidious and Plagueis had to coax from the dark side its final secrets. In the intervening years he had actually come to appreciate Plagueis for the planner and prophet he had been. Such perilous machinations required two Sith, one to serve as bait for the dark side, the other to be the vessel. Success would grant them the power to harness the full powers of the dark side, and allow them to rule for ten thousand years.

p. 101

Even though Sidious did not know how to cheat death, it was a superb way to tempt Anakin to the dark side.

Although you've asked for only canon sources, the Legends novel Darth Plagueis is worth mentioning since it provides a story of Plagueis' murder that is consistent with the canon information about Plagueis.

In the novel, Plagueis helped Sidious maneuver himself into position to be elected Supreme Chancellor of the Republic. Plagueis' plan was that Palpatine would appoint Hego Damask (Plagueis' public identity) co-chancellor and Plagueis would rule behind the scenes:

[Sidious:] "...my knowledge of the dark side will never equal yours. The title [of Supreme Chancellor], the crown, should be yours.”

[Plagueis:] “And it will be, once you openly appoint me co-chancellor. Feared and respected by the galaxy’s most powerful beings, Hego Damask will be seen as a windfall for the Republic. But even then I will advise only in secret from behind your throne.”

p. 188

Sidious, however, was too power-hungry to agree to that plan. When Sidious murdered Plagueis he revealed a long list of complaints against Plagueis, some of which hint at why Sidious chose to murder Plagueis before learning how to cheat death:

"...It was Hego Damask as Plagueis who then set his sights on a seemingly confused young man and, with meticulous skill, manipulated him into committing patricide, matricide, fratricide. Darth Plagueis who took him as an apprentice, sharing some of his knowledge but withholding his most powerful secrets, denying the apprentice his wishes as a means of controlling him, instilling in him a sense of murderous rage, and turning him to the dark side.”


“Plagueis, who turned away from the Grand Plan to focus entirely on himself, in an egotistical quest for immortality.


“Plagueis who attempted to turn his equally powerful apprentice into a messenger and mere intermediary.


Sidious paused, then, in derision, added, “Plagueis the Wise, who in his time truly was, except at the end, trusting that the Rule of Two had been superseded, and failed to realize that he would not be excused from it. Plagueis the Wise, who forged the most powerful Sith Lord the galaxy has ever known, and yet who forgot to leave a place for himself; whose pride never allowed him to question that he would no longer be needed.”

p. 356

Sidious felt that Plagueis was hiding secrets (like how to cheat death) from him and that Plagueis never planned to teach him, so there was no point in keeping Plagueis alive longer. Sidious also felt that Plagueis was no longer necessary for Sidious to enact his political plans and attack against the Jedi and Republic. Since Sidious felt that Plagueis was no longer necessary, Sidious decided to grab all the power for himself.

While not canon, this story is consistent with what we know about Plagueis and with Sidious' power-hungry character.


It was a ruse

It is uncertain if Darth Plagueis actually knew how to prevent death canonically. Consider the following:

"To cheat death is a power only one has achieved, but if we work together, I know we can discover the secret."― Palpatine

This implies Sidious does not know how to prevent death. Hence your question. However he also said...

"Unfortunately, he taught his apprentice everything he knew" ― Palpatine

But if we take that quote at face value, Sidious knew everything that Plagueis knew, insinuating that Plagueis didn't know how to cheat death either. But earlier in that conversation Sidious said that Plagueis did know how to prevent death.

"He had such a knowledge of the dark side, he could even keep the ones he cared about from dying." ―Palpatine

So obviously Sidious is BSing Anakin somewhere along the line. There is no evidence that Sidious knew how to stop death, so it would stand reason that it was not something that Plagueis ever knew either. Remember, canonically, Plagueis is no longer responsible for Anakin coming into being (courtesy of Disney), so there is no canonical evidence he truly knew how to create life or prevent death.

In short, it was all a ruse to lure Anakin to the Dark Side.

  • 2
    @TimSparrow - Yeah, Legends has a whole book on Plagueis (great read) which would have directly contradicted my answer. It's been awhile since I read it, but if I recall correctly, Palpatine didn't think it possible, and never found out that Plagueis succeeded until after he had killed him. Unfortunately, the book was decanonized.
    – amflare
    Commented May 9, 2017 at 13:43
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    @TimSparrow - Yep, Darth Plagueis by James Luceno
    – amflare
    Commented May 9, 2017 at 14:32
  • 1
    @Terriblefan - Uh... no? That assumption is both non sequitur and it fails Occam's Razor.
    – amflare
    Commented May 9, 2017 at 15:14
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    @amflare You never once question if Sidious was lying when he said he learned everything. You assume he didn't, while talking about the lies he tells his student. It is neither non sequitur nor illogical; it's a judgment of the things you take for granted. But that's neither here nor there. What matters is that Sidious was weaker than his master, which means he didn't have more knowledge than him; literally, knowledge in the dark side is power.
    – user40790
    Commented May 9, 2017 at 15:53
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    @Terriblefan - That's fair. However killing Plagueis in his sleep does not imply that Sidious was weaker. Because simply put, that would have been the easiest way to handle the situation. Which is something Sidious has an MO for doing. Regarding the assumption that Sidious told the truth about knowing everything, I'll grant that. More likely, Sidious knew everything about everything that he felt was worth knowing. I would not doubt that Plagueis withheld information. But Sidious does not have a history of throwing away advantages, quite the opposite. So it made more sense that that was the lie
    – amflare
    Commented May 9, 2017 at 16:02

     In novel Darth Plaguesis, Palpatine did learn how to cheat death, but only in others. Like his master, he could not save himself while dying, because at that moment he didn't have required concentration to work with Force. Consider following passage:

“There’s the rub, you see,” Sidious said in a philosophical tone. “All the ones you experimented on, killed, and brought back to life … They were little more than toys. Now, though, you get to experience it from their side, and look what you discover: in a body that is being denied air, in which even the Force is failing, your own midichlorians can’t accomplish what you’re asking of them.” Hatred stained Sidious’s eyes. “I could save you, of course. Return you from the brink, as you did Venamis. I could retask your body to repair the damage already done to your lungs, your hearts, your aged brain. But I’ll do no such thing. The idea here is not to drag you back at the last moment, but to bring you to death’s door and shove you through to the other side.” Sidious sighed. “A tragedy, really, for one so wise. One who could oversee the lives and deaths of all beings, except himself.”

EDIT: Darth Plaguesis is of course part of the Legends, but since lot of people like this book, and since we don't have lot of canon information, I think it is appropriate to include it.

  • 1
    OP asked for canon sources, but Darth Plagueis is not canon.
    – Null
    Commented May 9, 2017 at 22:51
  • @Null, as you mentioned yourself, information in canon is limited. Since you did quote from Darth Plagueis, I thought it is appropriate to mention most relevant passage.
    – rs.29
    Commented May 10, 2017 at 6:21
  • A lack of canon information is no excuse to post a Legends-only answer on a question that specifically asks for canon sources. I quoted Darth Plagueis as a supplement, but my answer provides a canon-only explanation. Your answer attacks the premise of the question with only a Legends source; it is essentially a non-answer given the OP's requirement that you use canon sources.
    – Null
    Commented May 10, 2017 at 14:59

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