From an individual perspective, a practical definition of 'Truth' may be said as: "Truth is the set of all useful coherent ideas/theories based on ONE logical system". For example, I didn't expect to see what I may call 'god' to discover useful theories  based on it, for my life. As I also didn't ask to see/touch the 'Geometrical Dot' exactly as it is defined at school, before I took advantage of any applied ideas in Gemotry based on this dot and which cannot exist other than in my mind in the least. I may add that one of the obvious results of the new definition of 'Truth' is that as long one cannot trust fully his own developed logical reasoning, he has no way but to follow 'by faith' some other's truth. In that respect, I may call myself "an individual christian by reason, not faith" since, to my big surprise, the hints in Jesus sayings were able to find their place in my 'logical' Truth.