On the Forth Day of Yule - The Yule Tree

The practice of bringing a whole tree into your home of the Yule/Christmas is a relatively modern German invention, which started in the 16th - 17th Century.  But the tradition has Pagan roots ... no pun intended :-)

Our Pagan ancestors held special meaning to any plant that remained green all year and it was custom to bring these evergreens inside and decorate their homes during the Yule season.  The evergreens were also believed to ward off evil spirits, illness and witches.

Egyptians particularly valued evergreens as a symbol of life's victory over death. They brought green date palm leaves into their homes around the time of the winter solstice.

Early Romans marked the solstice with a feast called the Saturnalia in honor of Saturn, the god of agriculture. The Romans knew that the solstice meant that soon farms and orchards would be green and fruitful. To mark the occasion, they decorated their homes and temples with evergreen boughs.

In Northern Europe the mysterious Druids, the priests of the ancient Celts, also decorated their temples with evergreen boughs as a symbol of everlasting life. The fierce Vikings in Scandinavia thought that evergreens were the special plant of the sun god, Balder.

The Germanic peoples decorated their trees with fruits and and sweets.  We decorate our trees now with ornaments, tinsel and baubles ... all shiny symbols of abundance and the suns return

sources
thehistoryofchristmas.com
christmastreehistory.net