As you cannot have a sweet and wholesome abode unless you admit the air and sunshine freely into your rooms, so a strong body and a bright, happy, or serene countenance can only result from the free admittance into the mind of thoughts of joy and good will and serenity.

What It Means

This is a placeholder explanation generated by the low-overhead model. It interprets "As you cannot have a sweet and wholesome abode unless you admit the air and sunshine freely into your rooms, so a strong body and a bright, happy, or serene countenance can only result from the free admittance into the mind of thoughts of joy and good will and serenity." in the context of "James Allen, in As A Man Thinketh (1902), Ch. 3 : Effect of Thought on Health and the Body" to mean that wisdom is timeless.