“Christmas is a time that reminds us how deeply our lives are woven together. Just as the roots of trees share strength beneath the soil, unseen but vital, so too do we.
“Even with all the rushing around and familiar traditions, there is a quieter sense of what it calls out in us.
“There is a softness to the season that reminds us of something easy to forget; that what we do matters.
“Our words, our choices, and even the ways we look out for one another – they ripple outward, touching lives we may never see.
“At a time when life can sometimes feel fragmented or uncertain, the Christmas season invites us to remember the power of reaching out to one another with generosity of heart, understanding and hope.”
Guests at Saturday’s service at Westminster Abbey will include volunteers and charity campaigners who have worked to help others, and Catherine praised them for making an “extraordinary difference”.
She wrote: “The time, care and compassion you give, often quietly and unspoken, and without any expectation or recognition, make an extraordinary difference to the lives of others.
“As the year draws to a close, I hope this season brings you moments of peace and clarity, and that you too, feel surrounded by the same love and care that you offer so freely.”
Catherine’s husband, Prince William, is scheduled to give a reading at the service, and their children, Prince George, 12, Princess Charlotte, 10, and 7-year-old Prince Louis, will be in attendance, with other members of the royal family.
Katie Melua, Fisherman’s Friends, Griff, Hannah Waddingham and Bastille’s Dan Smith will perform, while readings will be delivered by famous faces including Kate Winslet, Joe Locke, Chiwetel Ejiofor and Babatunde Aleshe.