The archives are devices in which the Ancients can store part of their knowledge. SG-1 found the first one on P3R-272, in a sealed room. The device appeared on a wall when Jack passed through a circle meaning "the place of our legacy" in Ancient language.

The archive was not when Teal'c went by, but when Jack got near to have a closer look, it caught his head and downloaded the Ancient database into his brain. As a result, his brain began operating at over 90% capacity, as opposed to the typical 5 to 10%. The Asgard were impressed that his subconscious used this knowledge to lead him to Othala, where he asked their help.

The second library he used gave him not only the knowledge of the Ancients, but also some of their powers, like their healing ability.

We can stop and wonder a little about Jack's Ancient gene and the activation of the archives. I have indeed thought of two ways of explaining its presence:

• Whether Jack always had it, and we can then wonder if the cause of the non-activation of the archive with Teal'c was the presence of a symbiote or the absence of the gene;
• Or it is the second library which inoculated the gene to Jack: what use would it have been to know how to use the chair if one was unable to do it because of the lack of one gene?

However, we have an evidence that Jack always had this gene: in the episode 08-15, we see that he had activated long ago an Ancient communicator linked with Joe Spencer's.