The wind scatters one year's leaves on the ground ... so it is with the generations of men.
Your children are no more than 'leaves'. 'Leaves' too these loud voices of loyal praise, these curses from your opponents, this silent blame or mockery: mere 'leaves' likewise those with custody of your future fame. All these 'come round in the season of spring': but then the wind blows them down, and the forest 'puts out others' in their stead. All things are short-lived - this is their common lot - but you pursue likes and dislikes as if all was fixed for eternity. In a little while you too will close your eyes, and soon there will be others mourning the man who buries you.
The healthy eye must look at all there is to be seen, and not say 'I only want pale colours' - this is a symptom of disease. The healthy ear and nose must be ready for all sounds or smells, and the healthy stomach must accept all food in the same way that a mill accepts all it was made to grind. And so the healthy mind too must be ready for all eventualities. The mind which says 'my children must live', or 'there must be popular acclaim for all I do', is the eye demanding pale or the teeth demanding pap.
Life is short. And for me, the older I get, the more quickly life seems to pass. We look at leaves from a tree as fleeting. Buds on a tree in the spring, shade in the summer, brilliant colors in the fall and then dead and blowing on the ground - soon to be mulch for future generations of growth. Similar too is the life of humans as well as the voices of others, be they loyal or blaming. All of this is "short-lived" and all too soon, you and I will be dead, perhaps mourned by our children, and then soon enough, our children will be dead too. Do not let this passage overcome you with morbidity! Rather, wake up and appreciate the life you have now! Live and "suck out all the marrow of life!"
Part of being resilient is being able to accept anything and everything that is tossed your way. A person who is resilient could be said to be "healthy" in mind and spirit. This is what Marcus means when he says a healthy eye can take and see all the colors. It would be ridiculous for the eye to say it only wants to see some colors. The same goes for ear, nose, and stomach. Therefore, to apply this to the mind, we cannot dictate what is out of our control. We can do much to ensure our children live long lives, but in absolute terms, we cannot control everything. We cannot control with 100% certainty whether they get ill or not. Therefore, our healthy mind is only healthy when we are prepared and can accept these things.