(5.26) Even those who have much learning and faith
And who have sincerely applied great effort
Will become defiled by moral downfalls
Through the fault of lacking alertness.

Some practitioners put a tremendous amount of effort into studying and practicing Dharma.  They attend all the teachings they can, even if only by correspondence, they have been working hard for the center and going to all the festivals.  In their daily lives, they strive diligently to put the instructions into practice, be more generous, patiently accept adversity, not retaliate when harmed, etc.  Many practitioners have given up a tremendous amount for the sake of their practice, including their money, their spare time, their careers, their enjoyments including sex, and some even their spouses and children.  (Note, you do no thave to abandon these things to be a Dharma practitioner, but some have done so for the sake of their practice).  There are many sincere practitioners out there doing all of these things, year after year.  As a result, they have accumulated great virtues, tremendous merit, and profound wisdom.

The merit and wisdom accumulated through such effort are, without a doubt, our most prized possessions.  We go to great lengths to protect our external valuables, such as buying insurance for our home, car and physical health, we put locks on doors, use safes, created a banking system, put firewalls on our computers, passwords on our phones, security guards everywhere, police in the streets and armies deployed around the world.  The security industry is one of the largest industries in the world, indeed we can say that the entire “state system” that the world is organized by is itself an outgrowth of the need for security.  Trillions of dollars, millions of people, countless hours are all dedicated to security.  If protecting these external things is worth such effort, what need is there to say of the need for internal security of guarding the mind?  Our inner wealth of merit and realizations are far more valuable than anything external, yet more often than not we do nothing to protect such inner wealth.

A dam has the power to hold back a giant river, but it only takes one small crack for the whole thing to collapse.  For this reason, engineers on dams routinely monitor the integrity of the structure and diligently repair any potential weaknesses.  In the same way, our practice of virtue has the power to hold back the giant river of or delusions and negative karma, but it only takes one small crack for the whole thing to collapse and all our efforts are washed away.  The mind of alertness is our maintenance engineer who keeps a constant lookout for any potential weaknesses.  Without such an engineer, it is just a question of time before all that we have worked to build up in our mind is swept away by the powerful currents of delusion and negative karma coursing through our mental continuum.

(5.27) If I lack alertness, the thieves of the delusions
Will cause my mindfulness to degenerate,
And then steal even the merit I have so diligently gathered
So that I shall fall into the lower realms.

When Geshe-la opened the temple at Manjushri, he essentially gave three days of teachings on overcoming distractions.  He said distractions are like a thief that robs us of our spiritual life.  In the same way, all delusions are like thieves that enter into our mind, cause our mindfulness to degenerate and then steal away all of the merit we have worked so hard to accumulate.

It is said that one moment of anger towards a bodhisattva has the power to burn up aeons worth of merit we have previously accumulated.  Though perhaps to a lesser extent, this is true about anger towards anybody who has been particularly kind to us, such as our parents, teachers and so forth.  When personal computers first came out, they were much more unstable than they are today (hard to believe, but true).  People were advised to save their work every 5 or 10 minutes, because there was always a danger of the computer crashing and losing all of our hard work.  If we failed to do so, we would have to start over again completely from scratch.  In the same way, we work very hard to accumulate virtue and realizations.  But the delusions of our mind can quickly and easily cause our spiritual life to crash and we can lose everything we have worked so hard to accumulate.  Guarding alertness is like saving on our computer, it protects our spiritual work from being lost.  Delusions are like computer viruses which can infect our computer and steal all or passwords or corrupt our spiritual files.  We wouldn’t go on-line without anti-virus software protecting us, so too our mind of alertness is like a firewall keeping out unwanted delusions.