Don't block the rods with your thumbs, keep them free. Be
attuned to any sensation that could come from your belly. Keep
breathing with the throat friction, walking slowly.
When you cross a line:
The rods swing and position themselves parallel to the line. So to
determine the direction of the line, you just have to look at the
direction pointed to by your rods. It does not make any difference
whether the rods rotate to the right or the left, or one to each
side.
When crossing a line, just a fraction of a second before the rods
turn, a very ‘physical’ sensation can be felt in the belly. This is
what I will call the ‘belly signal’. Actually, it is not a very nice
feeling. The more toxic the line is, the more uncomfortable you
will feel in your belly. This is a simple way of determining how
toxic a line is.