A prince who is not wise himself will never take good advice

Do not advance uphill against the enemy, nor oppose him when he comes downhill.

Neither a statement nor its opposite can be both true at the same time in the same place.

1. labyrinth2. pugnacious3. sanction4. astronomical5. periodical6. ramification7. pneumatic8. voluptuous9. orthodox10. inscrutable11. predominate12. knell13. inextricable14. debauchery15. insemination16. formidable17. reverberate18. axiom19. rendezvous20. reconnoiter21. annihilate