“Tonatzin’s themes are religious devotion and blessings. Her symbols are soil and light. An ancient mother figure who nurtures people and all that dwells in the land, Tonatzin is the life and light of the world. Today She joins our festival as the originator of this holiday, Tonatzin.
Juan Diego, a Native American convert, was surprised when this Goddess appeared to him in 1531 in an ancient site of pagan worship and requested that the temple be rebuilt [Basilica of Guadalupe]. Juan Diego believed this apparition was Mary, and therefore he did as She commanded. To this day, people come here at this time of the year for the Goddess’s blessing.
While most of us cannot travel to Mexico just to implore Tonatzin, there is nothing that says we can’t honor and invoke Her at hour own home. Light a candle or lamp and place before it a potted plant or bowl of soil. This configuration represents Tonatzin’s presence in your home throughout that day. From here She can illuminate the shadows and generate the light of hope and joy for all whose who live here.
Carry a seed and some soil wrapped in a green cloth with you today. Name the seed after any earth quality you want to develop in your life, such as strong foundations or emotional stability. When you get home, put the seed and soil in a planter or your garden. Tonatzin’s magic is there to manifest growth for the seed and your spirit!”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
“In Aztec mythology and among present-day Nahuas, Tonantzin ‘Our Revered Mother’ is a general title bestowed upon female deities. Informants of Sahagún, for example, called a frightening Goddess of war and childbirth, Cihuacoatl, by this title. The title is particularly believed to refer to Mother Earth.
Goddesses such as ‘Mother Earth’, the ‘Goddess of Sustenance’, ‘Honored Grandmother’, ‘Snake’, ‘Bringer of Maize’ and ‘Mother of Corn’ can all be called Tonantzin. Other indigenous names include Chicomexochitl (‘Seven Flowers’) and Chalchiuhcihuatl (‘Woman of Precious Stone’). A Tonantzin was honored during the movable feast of Xochilhuitl.
Mexico City‘s 17th-century Basilica of Guadalupe –built in honor of the Virgin and perhaps Mexico’s most important religious building—was constructed at the base of the hill of Tepeyac, believed to be a site used for pre-Columbian worship of Tonantzin. Coatlaxopeuh meaning ‘the one who crushes the serpent’ and that it may be referring to the feathered serpent Quetzalcoatl.” 
There is an interesting story told of this encounter between Juan Diego and Tonantzin. “The story is told in the Nican Mopohua, a poem written in Nahuatl (the Aztec language)…most probably written in 1556 by the Nahuatl native speaker Antonio Valeriano.
In the poem the Lady not only appears as an ordinary dark-skinned indigenous woman and speaks to Juan Diego in his Nahuatl mother tongue but She treats him with affection and respect, as an equal. (She speaks to him standing up; if She had been a noble, She would have received him sitting down.) She addresses him in familiar language, using many diminutives, like a mother. The indigenous Nahuatl people had seen their world destroyed, their great capital city in ruins, their culture and religion smashed. An estimated population of 25 million when the Spaniards arrived declined by the end of the century to 1 million from conquest, disease and suicide. The psychological trauma must have been devastating. But the Lady tells Juan Diego She is the Mother both of the Christian god (Dios) and the supreme Nahuatl god and She repeats some of that god’s highest titles (Life-Giver, Creator of Humanity, Lord of the Near and Together, Lord of Heaven and Earth). When Juan Diego says he is of too humble status to speak to the bishop, She insists he is Her chosen messenger and he ends up carrying the good news to the bishop (‘evangelising’ him). The Lady represents the female aspect of the divinity (the Nahuatl supreme divinity Ometeotl being both male and female – the Divine Pair), the nurturing Earth Mother. She tells Juan Diego: ‘I am your kind mother and the mother of all the nations that live on this Earth who would love me.’ She accords the poor equal, or even greater, dignity than the rich and equally assumes both Christian and Nahuatl names of the great ‘Life-Giver’.” 
Livingstone, Dinah. Sofn.org.uk, “Tonantzin Guadalupe – ‘Our Mother’“.
Barnett, Ronald A. Mexconnect.com, “Our Lady of Guadalupe: Tonantzin or the Virgin Mary?”
Maestas, Julia. Beinglatino.us, “Guadalupe or Tonantzin: Culture, Identity and Feminine Empowerment“.
Mexicolore.co.uk, “The Virgin of Guadalupe and Tonantzin“.
Wikipedia, “Huei tlamahuiçoltica“.