Other translations: Take up the Three Primary Resources. Three Things Maintain Inseparably.
Jamgon Kongtrul wrote:The primary resources for working at dharma are a good guru, the proper practice of dharma with a workable mind, and suitable conditions for dharma practice - food, clothing, and so on. If these three are all available to you, take joy in that and pray that they be available to others, too. If they are not all available, meditate on compassion for others and take on yourself the deficiencies that all sentient beings experience in these primary resources. Pray that you and all others may have them.
Dilgo Khyentse Rinpoche wrote:
The three essential factors on which the accomplishment of the Dharma depends are: to meet with a qualified teacher; by receiving the instructions, to cultivate the correct attitude; and finally, to have the necessary material conditions.
If we do not follow a genuine master, we will never know how to practice the teachings. If the Buddha had not turned the Wheel of Dharma, we should not know what actions we should do and what actions we should refrain from. How can we, who have not had the fortune to meet the Buddha in person, practice the path of liberation if we do not follow a master? How else could we recognize paths which are mistaken and inferior? Moreover, just as we treat stiff leather with oil to make it smooth and supple, so too we should practice the teachings correctly, with a calm and docile attitude, undisturbed by afflictive emotions. Finally, living in the realm of desire, as we do, we find it impossible to practice the Dharma if we lack food to fill our stomachs and clothes to cover us against the wind.
If we have these three essential factors complete we should be happy at the thought that we have all that is necessary to practice the teachings. It is as though we have been equipped with a good horse for an uphill journey: the way will be without difficulty. And we should pray that all beings might be just as fortunate.
If, however, we do not possess all of these essential factors, we should reflect that though we have entered the Buddhadharma and received plenty of teachings and instructions, we still lack the conditions suitable for practice.
As a matter of fact, there are many disciples who are unable to practice properly because of this shortcoming. They have what is known as 'good karma going wrong.' As was explained before, 'Old yogis getting rich; old teachers getting married.' We should feel sorry for such people and pray from our hearts that the cause of their not having such favorable conditions might ripen on us and that, as a result, their situation might be improved.
CT's commentary pretty much repeats what Jeff already posted, but I included it because I really like the line, "you can afford to practice." Money/time are a favorite excuse to not do any number of things, but CT is direct: now that you have these, what's your excuse for not practicing? By definition nearly any reason is rooted in delusion. Why? Because A) some form of practice is always possible, even the aspiration to be able to practice as JK said, and B) nothing less than our complete and total liberation from all troubles, including the ones which hamper Dharma practice, is at stake.Chogyam Trungpa wrote:The first cause is having a good teacher. The second cause is applying your mind and basic demeanor to the dharma. The third cause is having food and housing so that it is possible for you to practice the dharma. You should try to maintain those three situations and take delight that you have such opportunities.
To take on the first principal cause is to realize the necessity of the teacher, who actually allows you to get into situations. To take on the second principal cause is to realize that one's mind must be tamed. For instance, your mind might be into a business deal, or a teaching deal, or a book-writing deal, or into making a funny kind of monumental experience for yourself... This attitude was not all that prominent when Jamgon Kongtrul wrote his commentary on the slogans, but today we have a lot more choices.
To take on the third principal cause is to realize that it is possible for you to practice the dharma because of right circumstances, because you have taken an open attitude toward your life and have already worked out some kind of livelihood. Your food and clothes and shelter are taken care of, so economically you can afford to practice.
My own takeaway is that the slogan is a friendly poke in the ribs: hey, you found the Dharma, you have people teaching you, and you have a sound enough body and mind to make use of this... Get a move on!
(edit: got mixed up on the DKR commentary, this is the correct one now!)