The glimpse of Protoss that we get in StarCraft II (until the release of Legacy of the Void) is through the experiences of a single Protoss mystic, Zeratul. Zeratul is on a sort of spirit journey to understand ancient prophecies about the end of the universe. He believes that understanding these predictions will give all three races the direction they need to avoid apocalyptic catastrophe. For the Protoss (at least this particular one), power begins with knowledge and understanding, which directs further efforts at power.
Rather than rushing into power to subjugate enemies or create even greater power, Zeratul wanted to know how power should be used and what should be done. He wanted mastery over context and direction, and certainty in his goals. Zeratul relied on writings from the past about the future to know what to do in the present. This optimizes his context and understanding, as it allows him to see the direction of forces by understanding the causes of their shapes. By understanding the origins of the Zerg, he understands the potential for Kerrigan to become powerful enough to thwart the overarching threat to the universe. By understanding the tensions between the three races, he understands the risk of Kerrigan’s destruction that would make possible the end of all things. For Zeratul, this view—brought by knowledge and understanding—is the most important resource. He wishes to begin at the beginning, and understand what should be understood.