Historical clue formulations

• Hidden — 2023-06-12
• Like puppeteers, usually — 2020-09-06
• Invisible — 2018-05-12
• Invisible — 2012-06-18
• Out of sight — 2007-10-09
• Invisible — 2006-07-18
• Seemingly not there — 2006-07-09
• Invisible — 2001-06-10
• Like the Shadow — 2000-12-22
• Hidden — 1995-12-27
• Invisible — 1994-05-08