Slipping Out of a Sandwich

Two holidays extraordinary bookend a day - simple, ordinary How is that unfortunate day viewed sandwiched between the other two Well, strange as it may seem and believe me, this is no dream That simple day, upon further reflection has the advantage of science-based refraction Picture each holiday as a separate painting each one glorious, majestic, self-sustaining Then give a two-sided mirror to our 'Day Ordinaire' Voila! ~ Now, which of the three days is 'Extraordinaire'