Kautilya's Arthashastra 9.1.3

9.1.3

svayaṃ hi rājā śūro balavān arogaḥ kṛtāstro daṇḍadvitīyo 'pi śaktaḥ prabhāvavantaṃ rājānaṃ jetum //

My teacher says that of enthusiasm and power, enthusiasm is better: a king, himself energetic, brave, strong, free from disease, skilful in wielding weapons, is able with his army as a secondary power to subdue a powerful king; his army, though small, will, when led by him, be, capable of turning out any work. But a king who has no enthusiasm in himself, will perish though possessed of a strong army.