Let's start from at the end. My father has often said that he really feels Shabbos is over right at the end of Havdalah, when the Havdalah candle gets extinguished, with a quiet hiss, in the Havdalah wine.
The beginning of Shabbos also has powerful moments. Sometimes you feel it while singing Lecha Dodi during Kabbalat Shabbat in shul. Sometimes you feel it as you stroll home. And many feel it when when giving the customary Friday-night blessing to their children. As you lay a hand on your child's head, your heart fills with hopes for the future...of a blessed home and family, and a firm connect with Our Father in Heaven.
Today I came across a very poignant description of that blessing from the perspective of a little girl now grown up, Slovie Jungreiss-Wolff.
"When I was a little girl one of my favorite places in the world to be was in my grandparents’ home. They had been deported to Bergen-Belsen, lost an entire world, and were cut by the shards of pain and suffering that tragic time would bring. Yet despite the darkness of their lives, they gave me only love.
"When my Zayda would bless me, his soft, white beard would flow over my face. I felt safe, even strong somehow. He would place his hands on my head, whisper the holy words and cry.
"I was named for my Zayda’s mother, who was killed in Auschwitz. Perhaps the grief of the past and the hope of the future collided."