...is for people who fail to learn the lessons of life. They may repeat the same mistakes over and over, such as taking a succession of identical jobs and being surprised to find each one unfulfilling. They may also see others making a mistake and fail to apply the lesson to their own lives. They go right ahead and make the same mistake themselves.
It's good to move on and leave the past behind, but in a Chestnut Bud state we are almost too ready to do this. We give so little thought to the past that we fail to learn and are doomed to repeat our failures. Chestnut Bud helps us learn and move on to genuinely new experiences.
Dr Bach's description
For those who do not take full advantage of observation and experience, and who take a longer time than others to learn the lessons of daily life. Whereas one experience would be enough for some, such people find it necessary to have more, sometimes several, before the lesson is learnt. Therefore, to their regret, they find themselves having to make the same error on different occasions when once would have been enough, or observation of others could have spared them even that one fault.
- The Twelve Healers and Other Remedies
Quoted from http://www.bachcentre.com