Adhering to one's principles is not the same as attachment. Adhering to our principles amidst temptations and difficulties is a positive force for improvement. Attachment is self-centered concern about fame and gain, which keeps us bogged in delusion.
Buddhadharma represents "flawless wisdom", which teaches us to let go of the self, that is, self-centeredness and selfishness.
Spiritual practice can give one a tranquil mind, which can then be followed by wisdom. In terms of meditation, concentration means a progress of practice from a scattered, chaotic mind to a focused mind, and then to a unified mind, at which point one will have more objectivity. In terms of Chan, selfless wisdom is achieved when one lets go of one's self-centeredness and hence becomes undisturbed by the environment.
If you don't handle your own or others' matters in a self-centered way, you won't cause harm to others and won't bring trouble on yourself. This is wisdom. Knowledge is not necessarily wisdom. Wisdom means objectivity and freedom from self-centeredness. We gain wisdom by reading the