Sundials indicate the movement of the Earth. A gnomon casts a shadow which travels across the face of the sundial. Each sundial must be designed for an exact location, otherwise it will only reveal the dialler's ignorance of sundialling. Adaptation to a precise location is a good principle in all garden design. The length of the shadow cast by a sundial's gnomon depends on the time of year, the latitude of the dial, and the position of the earth on its daily rotation. No two identical sundials, in different gardens, will cast shadows in the same position at the same time. Sunlight itself is produced by the conversion of hydrogen to helium and takes 8 minutes to travel the 149.6 million kilometres from sun to earth. It is little wonder that sundials induce contemplation. They were placed on church towers, because "time is a sacred thing'. When mechanical clocks became available, the demand for sundials increased: they were needed to set the clocks. When other ways of setting clocks became available, many old sundials were moved into vicarage gardens.
English sundials have been inscribed with mottoes since the beginning of the sixteenth century. Mrs Alfred Gatty, a parsons's wife, gave the reason: "What could be more natural to a scholarly and reflecting mind than to point the moral of passing time in a brief sentence which arouses thought. (Gatty, 1890)" She produced a book of sundial mottoes and wrote that "The great Creator, who made the sun to rule the day and the moon and the stars to govern the night, has adapted our nature to these intermitting changes, and implanted in us an immediate desire to count how, drop by drop, or grain by grain, time and life are passing away."
The oldest sundial mottoes are in Latin and have a religious theme, often imbued with northern gloom:
HORA FUGIT, MORS VENIT: Time passes, death advances.
FERT OMNIA AETAS: Time bears all away.
DOCET UMBRA: The shadow teaches.
MANEO NEMINI: I wait for no one.
MEMENTO FINIS: Remember the end.
SIC TRANSIT GLORIA MUNDIS: So passes the glory of the world.
The best-known sundial motto, TEMPUS FUGIT, has become trite, but Thomas a Kempis' line from Imitatio Christi, the last example in the above list, has a majesty that is undimmed by repetition. So does St Paul's advice to the Ephesians:
SOL NON OCCIDAT SUPER IRACUNDIAM VESTRAM: Let not the sun go down upon your wrath.
Other sundial mottoes are humorous, though most wit dulls after a few centuries in a damp garden:
Time wastes us all, our bodies and our wits;
But we waste time, so time and we are quits.
What is the time? come, why do you ask?
Is it to start, or to end your task?
Love of riddles and puns has touched the sundial. WE SHALL ____ is proclaimed by a number of sundials. Should the possessor of a lively mind pass by, the words "dial' or "die all' will come to her.
The idea of a sundial engaging in conservation with the viewer is not uncommon. Dials generally have the best of it:
SOL ME VOS UMBRA REGIT: The sun guides me, the shadow you.
SENESCIS ASPICIENDO: Thou growest older whilst thou lookest.
REDIBO, TO NUNQUAM: I shall return, thou never.
I AM A SHADOW, SO ART THOU.
I MARK TIME, DOST THOU?
HORAS NON NUMERO NISI SERENAS: I count the bright hours only.
It has been noted that the last motto in the list is "either totally useless or utterly false'.
Sundials can stimulate a child's interest in science and life. Mrs Gatty herself became interested in sundials as a girl. Her father, the chaplain in whose arms Nelson died at the battle of Trafalgar, was the vicar of Catterick. It was a sundial over the church door that awakened his daughter's interest in the subject
One can imagine the awe that the Latin inspired in the child's heart:
FUGIT HORA, ORA: The hour flies, pray.