These verses clearly show the difference between man and beast. While Solomon is cast down at this moment, he still knew that the man's spirit went upward (to God) at the point of death, while a beast's goes downward to the earth with the body. Dogs, cats, etc do not have undying spirits within them. They are neither in heaven or hell at death. This may seem insensitive and unsentimental, but that is the truth of the matter. I have seen parents try to console a child after the death of a pet, and they tell their child that the dog, etc. is in heaven. Then, years later, they must undo that thought that they put there. While it may not seem harmful at the time, our children remember what is told them at very early ages. That is why we are to train up a child (early) in that proper way so that he will not depart from it when he is older.  

Then, Solomon launches into the next verse by talking about man's works. He says that rejoicing in one's works are our portion here below.  Remember the vantage point. When looking at life "under the sun" there is nothing else that man can glory in. We see many good people rejoice in their works, and the plain simple truth is that they are looking at things under the sun. If this life is all that we are seeing at the moment, then there is nothing else that we can rejoice in. Man is grass and as the flower of the field, he is here one moment and gone the next. That is the endurance of our works.   

Solomon even asks who shall bring man to look beyond these temporal things? What can bring man into realization that this world is not all that there is?  Where is the hope that one day we will be delivered
from the bondage of this death? Solomon comes back to that in the last chapter. "Remember now thy Creator.." The only way that one can see beyond this life and into a better one is to remember our Lord.  The only way that one can reach beyond their own works is to look with the eye of faith beyond the veil. The only way that one does not become of all men most miserable is to see (through faith) that One arose from the grave, and will soon return for us. While these bodies do go to the ground (the same as beasts), there will come a day when they will come out of the ground (different from beasts). Ever speed that day, and in the mean time, may we not focus on things "under the sun."