One of the most obvious aspects of science is that what today's scientists believe differs markedly from the past, as the science of each period has differed from that of its predecessors. Scientific belief is not static, but continuously changing, perhaps often in extensive or revolutionary ways. Of course it can occur that laws which were formerly well confirmed by repeated tests, in the future get refuted by new tests, thus causing a change in the body of empirical evidence, which may have been once favorable but becomes unfavorable as human experience of the world grows. This is one kind of change. But often change was understood as a case of "reducing" more restrictive narrow hypotheses to broader more general hypotheses. According to the consensus it was ideally possible to reconstruct the history of any science showing that what were originally conceived as general laws turn out to be more restricted cases of yet more general laws. (This was especially held in the case where Galileo's mechanics was seen as a restricted case of Newtonian mechanics and Newtonian mechanics subsequently seen as a restricted case of Einstein's relativistic mechanics.) In this way, change in science could be explained in terms of progress moving towards the ever more general all-embracing fundamental laws of nature encompassing an ever greater range of phenomena. If laws are regarded as "true" this progress could be seen as progress towards the truth about the world we experience.