Irregular past tense


Can anyone tell me what the reason is for how the past tense of the following verbs seems to be so different from the original word?

Βλέπω / είδα
Λέω/ είπα
Έχω/ είχα
Έρχομαι / ήρθα


Staff member
In the first two cases it's a different verb altogether that supplies the past tense:

βλέπω (same as in ancient Greek) -- είδα from AG είδον, from AG root Fid- (the same as Latin vid-eo)
λέω or λέγω from AG λέγω -- είπα from AG είπον, originally έFεπον, proto-Greek root eweikʷon

In the third case it is the same verb originally, having taken various forms through time:

έχω from Proto-Greek hékʰō, from Proto-Indo-European seǵʰo -- In the past tense formed with the usual ektasis (an e- added in the beginning): e(h)ekhon > eikhon είχον

In the last case it is again another verb that forms the past tense:

έρχομαι (same as ancient Greek) -- ήρθα, or ήλθα, from AG ήλθον, originally from AG root ελθ--, which gave also future tense ελεύθ-σομαι > ελεύσομαι (it's the same root that gave ελευθ-ερία, the act of coming and going freely).