It' a pretty stupid question, I know: How can I control the paragraph indentions for the output of some string?

str = StringRepeat[
  "This is some long string which should break into several lines. ", 
  4]

displays as:

I.e. The first line is indented to left by about 3 characters. I don't know why. The string is just an ordinary string with no special characters;

I was reading about ParagraphIndent and use it within Text, but his changes nothing (apart from the font):

Hence a simple Grid looks very strange:

Can anybody tell me, what I should do to get an ordinary paragraph with no first-line-indention?