Bhagavad Gita Verse 11, Chapter 14

sarvasvaareshu dehesminprakaasha upajaayate |
jnyaanam yadaa tadaa vidyaadvivriddham sattvamityuta || 11 ||
 
When luminous knowledge radiates through all gates of this body, then one should know that sattva has increased greatly.
 
sarvasvaareshu : in all gates
dehe : body
asmin : this
prakaashaha : luminous
upajaayate : radiates
jnyaanam : knowledge
yadaa : when
tadaa : then
vidyaat : one should know
vivriddham : increased
sattvam : sattva
iti : this
uta : definitely
 
What are the marks of sattva? Shri Krishna says that when we see radiance, or when we see knowledge radiating from a person, we should know that we are in the presence of a highly sattvic person. The word “dvaara” usually means door or gate, but here it refers to the sense organs, our doors to the world. Even though the sense organs are meant from receiving stimuli from the world, they can also convey our internal state to the world. Our eyes, especially, can give away our thoughts. If our mind is wandering, our eyes will also wander, for instance. In a sattvic person, radiance shines through the sense organs, especially the eyes.
 
Now, we should not think that a highly sattvic person will radiate beams of light from their body. But they do radiate calmness and peace. We can sense peace if we are near them, or pick up on their calmness if we are watching them on a screen. Watch Dr. Jane Goodall speak about her efforts to save gorillas in Africa, and you will be drawn to the serenity on her face instantly. Such people harbour few, if any, selfish desires in their mind. This lack of dirt in the form of selfishness lets their inner radiance, the light of their eternal essence, shine through.
 
From our perspective, whenever we notice an increase in clear thinking, we should know that sattva is predominant in our mind. If we see fried food but the intellect prevents our hand from reaching to pick up that food, we are in a sattvic state. If our thoughts are towards the well-being of the family, our city or our nation, instead of just our narrow well-being, we are in a sattvic state. If our mind is sharp and alert, if we don’t let anything drop in our personal and professional lives, we are in a sattvic state.

Bhagavad Gita Verse 62-63, Chapter 2

dhyayato vishayaanpumsaha sangasteshoopajaayate |
sangaatsanjaayate kaamaha kaamaatkrodhobhijaayate || 62 ||
krodhaadbhavati sammohah sammohaatsmritivibhramaha |
smritibhramshaad buddhinaasho buddhinaashaatpranashyati || 63 ||
 
When a man constantly thinks about objects, attachment for those objects arises. From attachment is born desire, and from desire is born anger. From anger comes delusion, from delusion comes loss of memory, from loss of memory comes destruction of intellect, and once the intellect is destroyed, he perishes.
 
dhyayataha : thinking
vishayaan : objects
pumsaha : individual
sangah : attachment
teshu : to those
upajaayate : is born
sangaat : from attachment
sanjaayate : is born
kaamaha : desire
kaamaat : from desire
krodhah : anger
abhijaayate : is born
 
krodhaat : when anger arises
bhavati : happens
sammohah : delusion
sammohaat : from delusion
smritivibhramaha : loss of memory
smritibhramshaad : from loss of memory
buddhinaasho : destruction of intellect
buddhinaashaat : from destruction of intellect
pranashyati : he perishes
 
Earlier, Shri Krishna touched upon the topic of continually thinking about material objects when we do not contact them physically. In this shloka, he goes into great detail as to why it is to be avoided. These two shlokas are sometimes referred to as the "ladder of fall". They illustrate how one simple thought can lead to the downfall of an individual.
 
Here is the entire sequence of events as mentioned in the 2 shlokas:
 
Constant thinking of material objects -> attachment -> desire -> anger -> delusion -> loss of memory -> destruction of intellect -> individual perishes.
 
Let's first examine the sequence of events from constant thinking all the way upto desire using the Ipod example from earlier :
A person has thoughts about ipod on sale -> gets attached to that ipod deal -> desire to buy ipod on sale is created.
 
Now, at this point, he has purchased the Ipod and is extremely attached to it. Even without going forward in the sequence, we can see that the material desire to procure an Ipod has taken the person away from performing his svadharma. His equanimity has already been disturbed. He is dragged back into the material world, and has taken one step backwards from moksha or freedom.
 
Let's move forward in the sequence:
Ipod breaks down -> he is angry that it has broken down -> he completely loses his equanimity -> takes anger out on his wife -> family environment is agitated.
 
Here, not only has he completely lost his equanimity, but has also caused pain to other members of his family. So the message here is that constant pondering and thinking about objects eventually leads to moving away from equanimity, hence it is to be avoided, or at least minimized to the extent possible.
 
An interesting point seen here is around anger. Per the shlokas, anger is caused when one's desire gets obstructed. Also, attachment to a concept such as one's job title or position causes continual waves of thought, anger and delusion, in other words, stress.  Therefore, these shlokas provide an ancient but relevant analysis of anger and stress.