(With) a grain of salt is a literal translation of a Latin phrase, (cúm) grano salis. A pinch of salt may also be used.

In common parlance, if something is to be taken with a grain of salt, it means that a measure of healthy skepticism should be applied regarding a claim; that it should not be blindly accepted and believed without any doubt or reservation. According to the Oxford English Dictionary “to take ‘it’ with a grain of salt” means “to accept a thing less than fully”. It dates this usage back to 1647.

Another meaning is ‘with moderation’, and it is related to the way someone uses something. It probably refers to the activity of cooking, where only a pinch of salt is sufficient to enhance the flavour of a dish. In this sense, using something ‘*** grano salis’ means to use it with moderation.

As President Reagan said, “Trust, but verify.”