This paper consists of various reflections and thoughts on the 20th century German philosopher Martin Heidegger. Heidegger's connection with the Nazis, his conflict with the logical positivists, the opposition of the logical positivists to the Nazis, a comparision of the main philosophical arguments of Rudolf Carnap and Heidegger and an analysis of particular parts from Heidegger's Being and Time are the main issues in the paper. Heidegger is a controversial figure because of his ties with the Nazi regime during the 1930's. On the other hand it is difficult to say that Heidegger's philosophical ideas and theories were an outcome of the Nazi ideology. However it is also a historical fact that unlike Heidegger, the logical positivists were in a state of resistance against the Nazis and had to pay the price with murder, exile and expulsion from their universities. Regarding the philosophical aspect, the logical positivists and one of their leading figures Carnap criticized Heidegger for developing a metaphysics which was unverifiable and devoid of a cognitive meaning. Carnap stated that such theories can only be regarded as an expression of a life-feeling, however that art does this in a more accurate way. Heidegger in turn criticized the logical positivists for their inability to understand an analysis of the Being of the human being in the framework of a fundamental ontology and also for reducing philosophy to logic and the sciences. Heidegger's ontology was to a significant extent influenced by particular previous philosophers. However one of the most interesting and original ideas in Being and Time is the analysis of the relationship between Being towards Death, anxiety and authenticity. Whether this analysis can be regarded as a metaphysical theory devoid of a cognitive meaning and be evaluated as an expression of a life-feeling is an open question