The innocent and the beautifulHave no enemy but time;
-copied from here.
Poul Anderson's Time Patrol series spells out that time brings experience and knowledge and therefore loss of innocence in at least one sense. See here. Maybe experience also brings temptation and therefore loss of innocence in the other sense? And time travel adds another dimension.
The phase, "no enemy but time," would make a good sf title. In fact...here.
Anderson's Time Patrolmen have perhaps mastered time but must contend with several other enemies:
individual time criminals, including Stane, Charles Whitcomb, Manson Everard and Luis Castelar;
the Neldorians, a whole age of bandits;
the Exaltationists, a smaller but more sophisticated group;
Lastly, there is another Guardians Of Time.