Origin of the term Red letter day
By the term ‘red letter day’ we mean, any day of special importance or specific significance, which may be related to a particular individual or a segment or a nation or in the history of mankind. Though the term is frequently used even today, its origin is rooted in classical antiquity. As it is often assumed, it did not originate from the medieval church calendars or a requirement that the important holy days should be marked in red from the First Council of Nicaea in 325AD.
The practice of marking important dates in red did not begin until the middle Ages. In fact, red ink was sometimes used in Roman calendars to identify the significant dates. The figures in red attracted their attention well in advance and enabled them to notice the days as a reminder, so that they could start preparing for them. Apart from that, in those days the red colour was also occasionally used for the important portions in a document. The reason is simply to highlight the noteworthy portions of the text.
Through the ages this practice continued until the middle Ages. In medieval manuscripts, initial capital letters and certain important highlighted words, known as rubrics, were written in red ink. At the same time, the important days, such as a saint’s feast or the Christmas or any other holy day, were also identified on medieval church calendars with the colour red.
As writing became more widespread, others quickly adopted the use of red ink in their writing, and the practice was continued, even after the invention of the printing press, including in Catholic liturgical books.
The first recorded use of the phrase in English was identified by William Caxton in 'The book of Eneydos' printed in 1490. However, the first print reference to 'red-letter day' is not seen until 1663, when Edmund Gayton wrote ‘The religion of a physician’.
Today, in many countries, it is the official practice of recognizing certain special days as ‘Red Letter Days,’ such as the Queen’s birthday in England or the day of independence in India.