In his book "The Tango of the Old Guard," Arturo Pérez-Reverte presents a thought-provoking perspective on doubt and certainty. He suggests that doubt is a vital force that keeps individuals feeling youthful and dynamic. When people embrace uncertainty, they remain open to new experiences and ideas, fostering a sense of curiosity and adventure that is often associated with youth.

Conversely, he portrays certainty as a detrimental concept, akin to a virus that leads to stagnation and, ultimately, old age. This notion implies that clinging to inflexible beliefs can hinder personal growth and creativity, trapping individuals in a state of complacency. Overall, Pérez-Reverte's insights highlight the importance of maintaining a questioning attitude to sustain vitality throughout life.