‘Teaching and training are unavoidable aspects of human growth. Since the dawn of civilization men have always craved for understanding everything that surround us, the whole cosmos and beyond, and in this process there always have been people – the ‘gurus, the teachers to transmit knowledge down to generations and also to create and acquire new knowledge. In this way teaching is one of the most natural and primary human acts, and everyone who knows something can teach those who want to lear something. But there are good teachers and bad ones too.