The parable of the blind men and the elephant, from Udana 6.4
For those interested in Buddhism, the Khuddaka Nikaya of the Pali Canon is often overlooked, but contains some really important texts, including the Khuddakapatha or "Short Passages." According to Thanissaro Bhikkhu (one of the translators of the text), the Khuddakapatha was probably originally used as an introduction to Buddhism for novice monks and nuns.
It is surprising how different the Khuddakapatha is from contemporary introductions to Buddhism. Among other things, the Khuddakapatha emphasizes the importance of making merit, includes a list of the 32 parts of the body, and includes instructions for metta ("loving-kindness" or "goodwill") meditation, but not for mindfulness of breathing (which nowadays is commonly the first meditation technique taught to novice meditators).
In addition to the Khuddakapatha, other important but often-overlooked texts from the Khuddaka Nikaya include the Udana, Itivuttaka, and Sutta Nipatha. In terms of their importance for understanding early Buddhism, these should probably be among the first texts one reads, but I am just now getting around to them.
The Khuddaka Nikaya does contain one text which is very popular and widely-read the Dhammapada. Indeed, the Dhammapada is probably the most frequently translated Pali text. Given the popularity of the Dhammapada, and to a lesser extent of the Jataka or birth tales of the Buddha, it is somewhat strange that the other texts of the Khuddaka Nikaya are but seldom translated, read, or discussed. Credit must go to Thanissaro and to the Thai Forest Tradition generally for helping to put the spotlight on these relatively neglected parts of the Pali Canon.