• Berakhot 5a teaches that one who is afflicted should examine his deeds, and if found blameless should attribute it to neglect of Torah — Ecclesiastes 6:1 "there is an evil that I have seen under the sun, and it lies heavy on mankind: a man to whom God gives wealth, possessions, and honor, so that he lacks nothing... yet God does not give him power to enjoy them" is the Talmudic curse-of-unfulfillment doctrine: the Sitra Achra's cruelest operation is the gift without the capacity for enjoyment, a precision tool for spiritual desolation.
• Sanhedrin 100a records a dispute about whether Ecclesiastes is canonical precisely because of its apparent pessimism — Ecclesiastes 6:7 "all the toil of man is for his mouth, yet his appetite is not satisfied" is the Talmudic anthropology of desire that the Sages canonized as holy: acknowledging the Sitra Achra's fundamental physiological weapon (the appetite that cannot be satisfied by physical means) is not pessimism but accurate field intelligence.
• Avot 4:1 (Ben Zoma: "Who is rich? One who is satisfied with his lot") directly reverses the Ecclesiastes 6 portrait: the Talmudic definition of wealth is self-generated satisfaction — the only form of possession that falls entirely outside the Sitra Achra's confiscation authority.
• Shabbat 77b teaches that everything God created has a purpose, including the fly, flea, and serpent — Ecclesiastes 6:12 "who knows what is good for man while he lives the few days of his vain life... for who can tell man what will be after him under the sun?" is the epistemological humility that distinguishes the Tzaddik from the Sitra Achra's agents, who claim omniscience about outcomes as their primary manipulation tool.
• Berakhot 55b teaches that a bad dream is worse than a flogging — Ecclesiastes 6:3 "if a man fathers a hundred children and lives many years, so that the days of his years are many, but his soul is not satisfied with life's good things, and he also has no burial, I say that a stillborn child is better off than he" is the Talmudic minimum-viable-life doctrine: the soul without satisfaction (menuchah) has been captured by the Sitra Achra's most complete operation, the hollowing of a life that has all external measures of success.