Historical clue formulations

• It's drawn between similar things — 2013-06-22
• Euclidean geometry's ___ postulate — 2011-06-08
• Aligned — 2005-10-16
• Similar — 2003-05-18
• Fated never to meet? — 2002-03-09
• Side by side — 2001-09-02
• Like railroad tracks — 1998-03-13