铅笔画不出的界限铅笔写不出的过去
[qiān bĭ huà bù chū de jiè xiàn qiān bĭ xiĕ bù chū de guò qù]
This implies something beyond one's ability. Pencils usually represent simplicity, fragility and inability in people's consciousness, meaning these things can't achieve with such an easy-to-do and common object.