A good cellar is first of all a place where one takes pleasure in contemplating one’s bottles, then choosing them before decanting them.
The temperature of a cellar is an essential parameter, the variations of which are welcome as long as they are measured. An average temperature of 14°C is ideal. There is no evidence that it should be stable, but if it does change it has to be very gradually.
The humidity must be high enough to prevent the dehydration of the cork, and therefore the evaporation of the wine; but not too much because the labels would degrade. A relative humidity level of around 75/80% is generally satisfactory.
For wines, aging is a way to become better. A new aromatic world reveals itself after fifteen or twenty years, deeper, more complex, more delicate and more mysterious.
Over the years, the wines gain smoothness without losing freshness or length. The only rule that matters is the pleasure of drinking them. Some great vintages can reach, after decades, a supreme level of refinement, elegance and complexity.
But most wines are actually delicious to drink from a young age: their fruit is so pure, their palate so full, powerful, but still harmonious.