Sentence:  The concept of unity , in which positive and negative are attributes of the same force , in which good and evil are relative , ever-changing , and always joined to the same phenomenon - such a concept is <WSD>still</WSD> reserved to the physical sciences and to the few who have grasped the history of ideas . 
Meaning of the word marked with <WSD> tags:  with reference to action or condition; without change, interruption, or cessation