On sadness, Montaigne notes the following:
The force of extreme sadness inevitably stuns the whole of our soul, impeding her freedom of action. It happens to use when we are suddenly struck with alarm by some really bad news: we are enraptured, seized, paralyzed in all our movements in such a way that, afterward, when the soul lets herself go with tears and lamentations, she seems to have struggled loose, disentangled herself and become free to range about as she wishes.
An individual can be petrified by extreme sadness. Such a notion was immortalized by Ovid who tells a story of a mother turned into a rock once she finds out that all seven of her sons have been killed in battle. Unprepared for the worst possible outcome, one leaves themselves open to such consequences. Here, the Stoic wisdom plays a role which states that you should always contemplate and reflect on the worst possible outcome whenever you act. In this manner, if that outcome comes about, you have a plan of action and can face the problem head-on.
On love, Montaigne has the following to say:
This is a source of the occasional impotence which sometimes comes so unseasonably upon men when making love, and of that chill produced, in the very lap of their delight by excessive ardor.
Excessive ardor. The excess of happiness. The excess of love, it all can be overwhelming just as an excess of sadness is. Virgil speaks of a woman dying when she faces a joy that she had thought to be unattainable, this unhoped joy overwhelms her.
The reason Montaigne speaks on these emotions is to further his point that in order to taste and digest pleasure, one must live moderately. Never too high, never too low and one way to accomplish such moderation is to understand the alternative possibilities, whether those possibilities are good or bad just so one is not shocked or taken aback when a different reality comes true.
Furthermore, moderation can be achieved through practice. Montaigne believed that through arguments one can practice daily toughness, to thicken one’s skin and prepare them for what life throws at them. These arguments being those that result in questioning one’s beliefs, attitudes and behaviors. Reflecting upon your action and noting the pros and cons on how to behave. Having a skeptical approach where one is always questioning and arguing, trying to get to the truth. In this manner, one is neither elated or depressed, for the search continues, always.