Edward Bernays (1891 - 1995) is considered one of the fathers of the field of public relations. He was one of the first to attempt to manipulate public opinion using the psychology of the subconscious. One of his favourite strategies was the indirect use of "third party authorities" to plead his clients' causes. He had a particular gift for the marketing strategy called the "tie-in" or "tie-up" in which an opportunity for promoting a consumer product is linked to another, e.g. radio and newspaper advertising.