The Sages are a group of humans who have dedicated their lives to researching the properties, chemistry and usage of a certain type of Eco. In reality, they do not play a much further part than in the first game (Jak and Daxter: The Precursor Legacy), though there are many references to eco sages in Jak and Daxter: The Lost Frontier.
In The Lost Frontier, Keira is on a quest to become an Eco Sage - although the type of sage she wants to be is unspecified, it can be assumed that she either wants to be a Green Eco sage after her father, or that she wants to be a general Eco sage (this is supported by the fact that she can convert Dark Eco into coloured Eco powers for Jak). She is shown channeling Eco at the end of the game, confirming that she is becoming a sage.
Tym is also revealed to be a Dark Eco sage, and had experimented with Dark Eco in the same manner that Baron Praxis did. He can also detect any being with a high amount of Dark Eco in their body - this is proved upon his first meeting with Jak and Daxter, stating that they both have a remarkable amount of Dark Eco flowing through them.
There is no Light Eco sage, but the Precursors can be considered the Light Eco sages due to the numerous links they have with Light Eco.
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