In 'Liberation in the Palm of Your Hand'(our modern day Lamrim) Pabongka Rinpoche, in Day 9 - 'The Optimum Human Rebirth' states:
"It sounds impossible that a red, slimy earthworm could surface out of the ground and prostrate itself to the Buddha. That is how impossible it has been for us earthworms to surface from the lower realms, take human forms, and even to go through the motions of studying and contemplating the Dharma".
This shows us, in no uncertain terms, that our precious human life, with all the 18 opportune conditions that would enable us to meet with and practice the Dharma, was impossible to acquire. Yet we have acquired them and furthermore, our Spiritual Guides are here to guide and direct us along a path, like the Lamrim, that has already been set out so clearly by our great masters, like Atisha and Je Tsongkhapa. Nonetheless, most of us still resist the firm and compassionate hand of our Spiritual Guide, much to our detriment.
However, most tragic is that the knowledge of this , which is part of the Dharma - the teachings of the Buddha- has evaded innumerable people, out there. Hence out of ignorance, when the going is rough, they choose the way out by deliberately snuffing out their lives, not knowing that , in doing so, they bring upon themselves more untold suffering . The worst suffering is to be cut off from the chance of an optimum human rebirth again, to meet with the Dharma again and , above all, to meet with a spiritual guide again.