Childhood: Plasticity and Vulnerability. A child's brain is highly plastic and goes through sensitive periods for language, attachment, and emotions. This plasticity is a strength, but also a vulnerability: early adversity leaves lasting marks. "Purity" is not a scientific concept; we speak more of openness and receptivity.

Adolescence: A Brain Under Construction. The reward system is highly reactive, while the prefrontal cortex, the seat of control and planning, continues to mature until around the mid-twenties. The attraction to novelty and risk is therefore normal, and this provides fertile ground for substance abuse. Studies link early initiation of alcohol or cannabis use to a higher risk of addiction and to developmental effects.

The young adult. Maturation continues: imperfection is biologically expected, and flourishing is a process.

Adulthood and Old Age. Neuroplasticity persists throughout life. Learning, staying active, maintaining social connections, and physical exercise are associated with better cognitive aging, a phenomenon known as cognitive reserve. Preparing for old age through mental renewal is therefore scientifically sound, though not guaranteed for all individuals.

Hinduism

The four stages of life (ashrama): the student (brahmacharya, mastery of the senses), the householder (grihastha, active life), the retreat (vanaprastha), and renunciation (sannyasa). The Gita (2:13) reminds us that the body passes through childhood, youth, and old age, while the Self remains. Discernment (viveka) protects against what seduces without nourishing.

Buddhism

The fifth precept invites us to abstain from substances that disturb the mind. The Buddha left the palace after witnessing old age, illness, and death: the stages of life open the way.

Confucianism

Confucius summarizes his life in stages: at fifteen, study; at thirty, steadfastness; at forty, no more doubt; until seventy, when he follows his heart without exceeding the bounds of reason (Analects 2.4).

Judaism

The Ethics of the Fathers (5.21) also establish stages: study at five, the commandments at thirteen, and wisdom later. The bar mitzvah marks the entry into responsibility.

Christianity

“Unless you become like little children, you will never enter the kingdom of heaven” (Matthew 18:3): the purity of childhood is to be rediscovered. Saint Paul: “Do not get drunk on wine, but be filled with the Spirit” (Ephesians 5:18).

Islam and Sufism

Every child is born into the fitra, the pure, original nature. The Quran forbids intoxicating drinks; yet Sufi poets sing of another intoxication, that of divine love.

The coat and the seasons

Childhood is a precious cloak, woven from a purity that nothing later will equal. We do not choose it: we receive it, and we wear it without knowing it.

Then comes adolescence, and with it the allure of intoxication. Alcohol, drugs, hurtful actions: so many fleeting worlds, shining for a moment before seeking to erode what is most essential within us. Adolescents are called to vigilance, not out of fear, but out of loyalty to what remains intact within them.

The young adult is not without flaws. Yet, imperfect and sincere, he moves forward towards his own fulfillment. Nothing requires him to be spotless; he is asked to begin.

Then comes professional life, a long season of labor. The mind must constantly renew itself, like water that is kept flowing, because each day prepares for an old age that can be a peak rather than a decline.

Thus the ages echo each other: the received cloak, the vigilance maintained, the initial impulse, the ever-renewed source. And at the end of the road, an ancient heart, clear as at dawn.