Historical clue formulations

• Thought spot — 2023-02-26
• "The ___ -- is wider than the Sky" (start of an Emily Dickinson poem) — 2021-01-24
• The thought is there — 2020-11-29
• Hard drive, essentially — 2019-08-07
• Einstein — 2019-06-14
• Scarecrow's desire in "The Wizard of Oz" — 2019-03-26
• Genius — 2019-02-03
• It's all in your head — 2012-02-24
• With 25-Across, a puzzle — 2011-02-13
• Cranium contents — 2010-06-14
• Smarty — 2010-01-19
• Major processing center — 2009-08-28
• Cranium contents — 2009-08-24
• Computer's center, informally — 2009-04-19
• Scarecrow's wish in "The Wizard of Oz" — 2007-11-26
• Word that can precede the starts of 17-, 35- and 54-Across and 16-Down — 2007-07-12
• Control center — 2003-10-22
• Genius — 2000-01-06
• Einstein — 1999-04-27
• Egghead — 1998-06-20
• Genius — 1997-04-16
• Einstein — 1994-03-24
• Whiz kid — 1994-03-07