To my son Tommy,
Science often struggles with seemingly contradictory items or states existing at the same time in the same space. In fact, you only have to look at two of the biggest ideas, quantum mechanics and relativity, to see the conundrum presented when they try to reconcile what they know of each to the other.
The heart, however, has no problem existing in two or more states at any one time, even if science or our own brains can't always reconcile this.
Take the feelings felt during Christmas. We feel joy and that is expected. But amongst the delight and exhilaration of the holidays, we also feel sorrow for the loss of those that have gone before us. Happiness and grief existing in the same heart simultaneously. Each tear that rolled from my eyes was filled with joy and sorrow, hopes and fears, love and pain, and we don't have to overthink it or understand it at all.
Merry Christmas to all, those with us here and present, and those with us in our hearts forevermore.