לזכות ידיד נפשי רבי אפרים בן מרים שושנה לברכה והצלחה בכל מעשי ידיו
The gemara in numerous places talks about the idea that kedusha spreads. So if one sanctifies the leg of an animal as a korban the kedusha spreads to the entire animal. If someone is mekadesh half a woman the gemara suggsts that the kiddushin should spread to the entire woman because the nature of kedusha is to keep spreading.
The contrast to kedusha is tyveh - raw desire. Tyveh ALSO has a nature that it spreads. There is a famous Ramban [on the pasuk למען ספות הרווה את הצמאה] who says that one tyveh leads to the next and it never ends. We actually see that in our world. Whatever people have gets boring after a while and they look for new, more exciting tyvos. Until they get boring and the search continues, ad nauseam.
The way to combat tyveh is by showing it that it is limited and can't just expand wherever it wants. The moment we show tyveh its limits we have disemboweled and disempowered it. That is the secret of the eitzah of the Raavad to stop yourself at every meal from eating something you wanted to eat. You eye that cake, you salivate - and then you say "NO, I will not have it" [and then you give it to your wife who is on a "diet"]. That is a TKO [technical knockout] to the power of tyveh. In such a way the person shows the tyveh that it doesn't possess the same power of kedusha to expand.
That is a GREAT tikkun!
