临渊羡鱼，不如退而结网 lín yuān xiàn yú,bùrú tuì ér jié wǎng[It is better to return home and weave net than standing by water and admiring fishes;one should take practical steps to achieve one’s aims; It is hard to catch birds with an empty hand; It is vain to fish without a hook, or read without a book] 比喻空怀壮志,不如实实在在地付诸于行动
比喻虽有愿望，但只凭空妄想，难收实效。
《汉书．卷五六．董仲舒传》：「古人有言曰：『临渊羡鱼，不如退而结网。』今临政而愿治七十余岁矣，不如退而更化。」