All things are preceded by mind, 
Mind is their master, they are produced by mind. 
If somebody speaks or acts 
With a purified mind, 
Hence happiness follows him, 
Like never departing shadow.

This verse is closely related to the previous one . If the mind is purified, the mental phenomena it creates are also pure. Therefore, joy and happiness follow as surely as suffering and sorrow in case of a defiled mind. As we can see from these two verses, happiness and suffering depends on us entirely, on our own minds, on the thoughts that we are harboring. There is no other way to happiness then purification of mind and ultimately, in destroying all the defilement completely and reaching the highest goal, the awakenment or Nirvana.

All mental phenomena are preceded by mind, 
Mind is their master, they are produced by mind. 
If somebody speaks or acts 
With a corrupted mind, 
Hence suffering follows him, 
Like the wheel the foot of the bearing animal.

In this verse,  some philosophical observations are made about the nature of our mind. It says that all the mental phenomena, happiness or suffering, joy or sorrow are made by, or are the outcome of, the quality of the mind. These mental phenomena are (according to the teachings of Abhidhamma) feelings (vedanā), perception (saññā) and volitional activities (saṅkhāra). And because these phenomena are created by, or so closely related to, the mind, they are always "colored" in the same way as the mind is. If the mind (as in this verse) is corrupted, full of evil thoughts, then only suffering and sorrow awaits us as a result of this. In other words, the mind, creating these mental phenomena simply creates them "to its own image". Therefore, negative thinking always brings with it suffering and sorrow, just as the wheel follows in the path of the animal carrying the charriot. We experience suffering only because our minds are not purified, we are not awakened. To purify the mind is to get rid of suffering once and for all.