"Between the daylight gambler and the player at night there is the same difference that lies between a careless husband and the lover swooning under his lady's window"

In this quote, Honore de Balzac draws a contrast in between 2 types of bettors: the "daylight bettor" and the "player at night." He recommends that there is a considerable difference between these two people, just as there is a distinction in between a "careless partner" and a "fan swooning under his girl's window."

The "daylight gambler" is likely somebody who casually engages in betting during the day, perhaps as a type of entertainment or to kill time. They may not take it too seriously and may not be fully invested in the result. On the other hand, the "gamer at night" is someone who is more devoted to gambling and may even be addicted to it. They want to keep up late into the night, risking everything for the excitement of the game.

Similarly, a "negligent spouse" is somebody who is not completely committed to their relationship and may take their partner for granted. They might not put in the effort to make their partner feel liked and appreciated. In contrast, the "lover swooning under his girl's window" is somebody who is deeply in love and will do anything to reveal their dedication. They want to go to terrific lengths to win over their beloved.

Overall, Balzac's quote highlights the plain contrast in between those who take part in activities without much idea or enthusiasm and those who are fully invested and committed. It also recommends that the latter group is most likely to experience extreme feelings and take greater threats.