Since you talk about programming, a few years ago I was called for a mission for a national firm to help them implement UML (Unified Modeling Langage) within their programers department. Why did they need me since for already two years they have been using the consultancy of a reputed specialist firm in that field I asked them ? Well their problem was that these specialists were totally abstract for their 50 programers 
. So there is a difference between abstract and concrete since the path between the two is not so evident 
. By coïncidence, I have just written before an essay I untitled UMO for "Unified Modeling Object" - unhappily I lost the paper and wouldn't even be capable to rewrite it - where I said that UML wasn't enough because it was just a mere convention of langage and not a method of conception by itself, that one needs one step further to really unify the Programming Objects World so I describe there the UMO where I unify everything to INTERFACE (you must be familiar with since Java or Microsoft COM architecture - with the amusing IUnknown Interface - strange name and I have found a funny story about that I will post it one day in chitchat ). I won't detail but I give this paper to some programmers and I was astonished that they didn't fear the level of abstraction since they didn't seem to much appreciate UML . So I accepted the mission and help them to implement UML with the dedicated tools like Rational Rose and a little RUP (Rational Unified Process). I then realise that contrary to most consultants in abstract field I have the advantage of being more concrete and that abstraction is not for me an end by itself but a mean. Concrete is the end but the realisation of a good ARCHITECTURE needs abstraction. Also the PROCESS of Abstraction by itself is CONCRETE although the object is abstract. This again rejoins Deming's philosophy of action: everything must at the end be concrete even the process of abstraction above. The inverse process - from abstract to concrete - is called REIFICATION and it is not EVIDENT because of details of REALITY that is why you cannot discard OUTER REALITY totally and think that all comes from your own mind at least when you are not God itself - if ever he exists or whatever he (it?) is .
I'm doing somehow the same approach in Finance modeling: I'm always looking for Unification see http://www.elitetrader.com/vb/showthread.php?s=&threadid=22833&perpage=6&pagenumber=6:
"As for my model one can either says that it belongs to none of these three schools or that it belongs to all these three since their paragdim opposes with each other whereas my paradigm embraces all of them and add a new emerging one so that I can say that my model is at the same time fundamental, technical and quantitative (I won't extend and only summarize the reasons why : it is fundamental because I dind't use any analogy of Physics as premisces but economic reasoning, it is technical because the results are consistently near what technical analysts obtain but with some adding perspective and precision, and quantitative because it is based on mathematical equations like in "pure" physics model which is not the case of technicals who mostly justify technical analysis with "psychological" fads and so called market's irrationality whereas I reestablish rationality and economical reasons in stock market fundamental dynamics without denying the role of psychology but psychology is no more a cause but an effect in my paradigm)."
. So there is a difference between abstract and concrete since the path between the two is not so evident . By coïncidence, I have just written before an essay I untitled UMO for "Unified Modeling Object" - unhappily I lost the paper and wouldn't even be capable to rewrite it - where I said that UML wasn't enough because it was just a mere convention of langage and not a method of conception by itself, that one needs one step further to really unify the Programming Objects World so I describe there the UMO where I unify everything to INTERFACE (you must be familiar with since Java or Microsoft COM architecture - with the amusing IUnknown Interface - strange name and I have found a funny story about that I will post it one day in chitchat ). I won't detail but I give this paper to some programmers and I was astonished that they didn't fear the level of abstraction since they didn't seem to much appreciate UML . So I accepted the mission and help them to implement UML with the dedicated tools like Rational Rose and a little RUP (Rational Unified Process). I then realise that contrary to most consultants in abstract field I have the advantage of being more concrete and that abstraction is not for me an end by itself but a mean. Concrete is the end but the realisation of a good ARCHITECTURE needs abstraction. Also the PROCESS of Abstraction by itself is CONCRETE although the object is abstract. This again rejoins Deming's philosophy of action: everything must at the end be concrete even the process of abstraction above. The inverse process - from abstract to concrete - is called REIFICATION and it is not EVIDENT because of details of REALITY that is why you cannot discard OUTER REALITY totally and think that all comes from your own mind at least when you are not God itself - if ever he exists or whatever he (it?) is .I'm doing somehow the same approach in Finance modeling: I'm always looking for Unification
see http://www.elitetrader.com/vb/showthread.php?s=&threadid=22833&perpage=6&pagenumber=6:"As for my model one can either says that it belongs to none of these three schools or that it belongs to all these three since their paragdim opposes with each other whereas my paradigm embraces all of them and add a new emerging one so that I can say that my model is at the same time fundamental, technical and quantitative (I won't extend and only summarize the reasons why : it is fundamental because I dind't use any analogy of Physics as premisces but economic reasoning, it is technical because the results are consistently near what technical analysts obtain but with some adding perspective and precision, and quantitative because it is based on mathematical equations like in "pure" physics model which is not the case of technicals who mostly justify technical analysis with "psychological" fads and so called market's irrationality whereas I reestablish rationality and economical reasons in stock market fundamental dynamics without denying the role of psychology but psychology is no more a cause but an effect in my paradigm)."
Quote from ematters:
In programming terms, abstraction means regrouping certain concepts together. Concrete means an instance of this abstraction that has its own existence. Hence I would say reality is both concrete and abstract. For example, I can describe a pair of boobs with many different levels of abstraction, one of them could be 'a tool to feed mammals when they grow up', another could be 'a handle for all sorts of fun'
). I would tend to beware of those 'architects' that have never hit a nail too 
