Arcana Coelestia # 9153
9153. 'If the thief is not caught' means, if there is no recollection of what has been taken away. This is clear from the meaning of 'if the thief is caught' as, if there is a recollection of what has been taken away, dealt with just above in 9151, at this point no recollection of it since it says 'if he is not caught'.
Isaiah 40:3
3
The voice of one crying in the wilderness: Prepare ye the way of Jehovah, make straight in the desert a highway for our God!