Book 2 (or Book II in Roman numerals (??!) which is how the contents of my translation are listed which is weird because as far as I know, Ancient Greeks didn’t use Roman Numerals…) but anyhow, the second book of a total of nine books of Herodotus the Histories concerns itself entirely of his visit(s) to Egypt, their Geography, their Customs, their History, their Tales – a kind of ancient travelogue. 
https://search.yahoo.com/yhs/search?p=egyptian+sphinx&ei=UTF-8&hspart=mozilla&hsimp=yhs-001
And if you think about it, The Histories is basically a war book mostly about the great wars between the Ancient Greek states and the Achaemenid Persian Empire (550-350 BC https://en.wikipedia.org/wiki/Achaemenid_Empire) so it seems a bit weird that he would include it at all in The Histories…much less as the second (the 2nd, the IInd, book; whatever), book which follows close on the heels, in fact right after, the first book, which seems to be setting the tone for the big Greek / Persian smack-down to follow; but no, he goes directly on vacation to Egypt instead. Hmm. (I just found out that “Hmm” is a word that Word recognizes as a word. Weird. No vowel. Hmm.)
Why did he do that? I’ve got some ideas, but please don’t use any of my ideas here in your Herodotus term-paper if you have arrived at my humble blog by internet-search thinking I am some kind of scholar or knowledgeable person about this stuff. I’m not. Clearly I’m not. I just dig it. And if you use any of my ideas, I just bet your professor will treat you to a big bad beat-down, because I’m almost sure he or she already has a pretty good idea (right or wrong) of why Herodotus wrote his Histories this way and you had best parrot those ideas and not mine. Just saying.
Keep in mind the Persians had already conquered Egypt (https://en.wikipedia.org/wiki/Battle_of_Pelusium_%28525_BC%29) by the time Herodotus visited. So it makes a kind of sense as a prelude to the Persian invasion of Greece to go into further Persian background and who they had invaded and conquered. I mean, these Persians; they’re bad dudes! IMHO, there is another dimension.
Remember good King Croesus and how he was a friend to the Greeks? And how Herodotus tells the tale that after Croesus falls, the local Greek colonies requested from the Persians the same deal they had with Croesus and the Persians were pretty much, no deal? Prelude to war for sure! Well, it ends up the Greeks were cool with the Egyptians too. And even though Herodotus points out that Egyptians were different in just about every way from everybody else, in the sense that their customs for shopping, weaving, relieving themselves, and the divisions of male/female religious roles were the reverse of everyone else. But he also points out that there were many similarities between Egyptian and Greek gods and goes so far as to claim that the Egyptian gods were the basis of the Greek religion. So they were soul mates in a sense. And Egyptian priests were forbidden from eating beans. As were the followers of the ancient Greek philosopher Pythagoras. Coincidence? I think not.
Recall the Persians were monotheistic – they were Zoroastrians (https://en.wikipedia.org/wiki/Zoroastrianism) and had little patience with the polytheistic Egyptians, and little regard for their culture. So I guess book 2 (II) does make sense as building toward a prelude to war between Greece and Persia by painting the Persians in a certain light by showing them in contrast to peoples the Greeks admired namely King Croesus and the Lydians and the Egyptians. And even though the ancient Egyptians were a bit eccentric, the Greeks liked them anyway.
Alan Olee Book Report 