QUESTION: I am kinda confused:
We have the two terms Amnesia and Anamnesis.
Here are two different word endings (-sia and -sis).
Could you please explain this?
ANSWER: Hello Andrew,
thank you for your interesting question. Your observation is, indeed, correct and it belongs to a more advanced lingual perception and function.
Yet, I can tell you that there is no mathematical rule to explain morphological suffixes and why they occur in the way they occur. Actually, even more than two could occur in the same stem, but one cannot create rules for word-formation in a way that will always give actual or usable words; we can only say how word groups are affected by several suffixes like those ones, what meaning does the anew-formed word have and try to get a first impression of this word-game.
As far as your question is concerned, a general observation would be, for instance, that nouns of the third declension - i.e. mnesis - tend to alter their suffix to -ia, when they become compound nouns with the commonly met privative prefix a- (or even dys- and some other ones). So, similar changes would happen as well to the following: lexis-dyslexia but also dialexis, pistis-apistia/dyspistia/eupistia, haeresis-authaeresia but also aphaeresis/ diaeresis/exaeresis/anaeresis, mnesis-amnesia but also hypomnesis/anamnesis etc.
As long as you keep the ending of the primary noun (declension) while you create compound nouns (e.g. mnesis--> anamnesis, hypomnesis) the word keeps the basic concept of its stem, but alters quite a bit the final meaning according to the prefix, which was in our case a prepositional one. If mnesis is the act of reminding, then anamnesis is a kind of "reminding to self" and hypomnesis "the act of being reminded by".
Now, the suffix -ia gives a broader meaning to the stem and makes a step further as if from an "object" to a "state" or "act". In this sense, lexis remains a kind of "word" when you create dialexis; rhesis remains a kind of "speech" when you create diarrhesis, pararrhesis, aporrhesis, but not when you change the suffix to -ia, that will bring them more to a "state" than to an "object". Finishing this, dyslexia/alexia, parrhesia, amnesia, dyspistia etc. would literally mean "the state of ..." or the "act of ..." rather than "object of".
To sum up, there is nothing wrong or peculiar in Greek word-formation, other than the fact that it doesn't work so mathematically or learner-friendly as one would expect. The challenges are to observe:
1. The development of the new meaning according to the prefix/suffix and
2. How declensions are affected by various prefixes/suffixes by frequency; so it's all a matter of training and exercising.
Please, let me know whether I can be of further assistance. I hope this was a bit of help for you. Have a good day, Andrew, and always luck with your Greek study and interests.
---------- FOLLOW-UP ----------
QUESTION: Thanks for the awesome answer!
I thought the suffix "-sis" had to do with something bad, eg psychosis. I guess I was wrong.
No, it doesn't mean anything negative. The suffix is actually -is. When an extra -s- is present, it comes from the stem of future verb-forms. Here are some examples:
leg-o (to say)--> legs-o (fut.) --> legs-is (lexis/λέγσ-ις-->λέξις)
psycho-o (to ensoul) --> psychos-o (fut.) --> psychos-is (ψύχωσις)
phy-o (to be born) --> phys-o (fut.) --> phys-is (φύσις = nature)
Other words, without that -s- of the future are: pol-is, hybr-is, met-is, iasp-is etc.
Have a nice evening, Andrew. Let me know whenever you need further assistance ;)