You have to have as many defences in place as you possibly can. But even then of course - and it's important to stress this - you cannot guarantee being able to prevent every attack or every kind of attack.
Without the hope of posterity, for our race if not for ourselves, without the assurance that we being dead yet live, all pleasures of the mind and senses sometimes seem to me no more than pathetic and crumbling defences shored up against our ruin.
We must pay greater attention to keeping our bodies and minds healthy and able to heal. Yet we are making it difficult for our defences to work. We allow things to be sold that should not be called food. Many have no nutritive value and lead to obesity, salt imbalance, and allergies.
For truth is strong next to the Almighty. She needs no policies or stratagems or licensings to make her victorious. These are the shifts and the defences that error uses against her power.
The middlegame I repeat is chess itself, chess with all its possibilities, its attacks, defences, sacrifices, etc.