There's this song from LiSA that I've been trying to understand the lyrics. However, there is something that is bothering me right at the start.
The first verse of the song reads as
and it gets translated as (watch the video with subtitles on, at 1:05)
I've found a reason to become strong
Now, what's bothering me is that we normally use 知っている to say that we know something. So I was expecting to see 知っていた for "I knew/I've found".
I think I understand the dilemma of 知る vs 知っている in the present, the latter being a change of state (of not knowing to knowing) and hence the usage of ～ている. But what if the verb is in the past? What are the differences between 知った and 知っていた, and why is the former used in the lyrics?