Why manufacturers were printing calendars to popularise their products?

By the late nineteenth century, manufacturers were printing calendars to popularise their products. Unlike newspapers and magazines, calendars were used even by people who could not read. They were hung in tea shops and in poor people’s homes just as much as in offices and middle-class apartments. And those who hung the calendars had to see the advertisements, day after day, through the year. In these calendars, once again, we see the figures of gods being used to sell new products. Like the images of gods, figures of important personages, of emperors and nawabs, adorned advertisement and calendars. The message very often seemed to say: if you respect the royal figure, then respect this product.