Chinese languages

I'm looking to get this phrase translated in classical chinese.. its for a tattoo so the nicest looking language is preferred and because its for a tattoo, 4 characters would be ideal.

The phrase is "When desire becomes obsession"

Any help is greatly appreciated

Thanks!

mabe 无法自拔 in chinese it means u cant help yourself doing sth
for referrence only

"When desire becomes obsession"... I like the sound of that! )

It's "当欲望变成痴迷" in Chinese.