can you briefly tell me the summery of the third book?
As per king Kohelet , the only good is to partake of life in the present, for enjoyment is from the hand of God. Everything is ordered in time and people are subject to time in contrast to God's eternal character.
Ecclesiastes
After the introduction come the words of Kohelet. As king he has experienced everything and done everything, but nothing is ultimately reliable. Death levels all. The only good is to partake of life in the present, for enjoyment is from the hand of God. 
who got ate by a whale in the bible UNANSWERABLE who is jonah? He is a prophet in the Hebrew Bible of the northern kingdom of Israel in about the 8th century BCE. what is the above mentioned book? It is the canonical collection of Hebrew scriptures, including the Torah. is there any poetic books too ? Yes, "Sifrei Emet". which are the five scrolls? The five relatively short books of the Song of Songs, the Book of Ruth, the Book of Lamentations, Ecclesiastes and the Book of Esther are collectively known as the "Ḥamesh Megillot" . what can you  tell me about the second short book? In most Christian canons it is treated as a history book and placed between Judges and 1 Samuel. how is the book structured? The book is structured in four chapters.
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Ecclesiastes [SEP] Summary
The ten-verse introduction in verses 1:2–11 are the words of the frame narrator; they set the mood for what is to follow. Kohelet's message is that all is meaningless. After the introduction come the words of Kohelet. As king he has experienced everything and done everything, but nothing is ultimately reliable. Death levels all. The only good is to partake of life in the present, for enjoyment is from the hand of God. Everything is ordered in time and people are subject to time in contrast to God's eternal character. The world is filled with injustice, which only God will adjudicate.