The Kli Yakar - Parshat Vayeshev

"So he [Yehudah] said, 'What is the collateral that I should give you?' And she [Tamar] said, 'Your signet ring, your cloak, and the staff that is in your hand.' So he gave them to her, and he came to her, and she conceived for him." (38:18)
 
The Kli Yakar explains that the collateral requested by Tamar possessed spiritual symbolism.

• "your signet ring" – the sign stamped in one's flesh: the holy brit milah
  
• "your staff" – the staff of kingship (Mashiach, the ultimate human king, descends from Yehudah)
  
• "your cloak" – the tzitzit which are attached to a four-corned garment
  

These three things protect a man. How so?

• Brit Milah – a reminder that one is holy and should direct his passions only for holiness
  
• Kingship – a Jewish king is commanded to refrain from having many wives, again to curb this passion
  
• Tzitzit – the mitzvah of tzitzit saves a man from immoral behavior
  

When Yehudah gave these away, he symbolically gave away any protection he had from giving in to his passions.
 
Yet at the same time, the Kli Yakar sees in this episode a larger and more profound meaning:

And the Midrash says that everything that happens to the fathers is an indication for the sons, even though the fathers did not intend it to be so.

And thus, this story details for you matters that occur within this episode in order to inform you what will happen to "the sons" at the End of Days because from this relationship, the Redeemer was born to the scattered lamb of Israel, to cast from them the tzafir and seir [breeds of goats] of the King of Greece [a spiritual metaphor] and the rest of the kings of the nations whose success goes forth first like a young goat, as we see in Gemara Shabbat 77b:
" 'Why do goats go forth first, and then the sheep?' and it concludes that 'it is like the Creation of the World: Darkness goes forth first and then the light.' "
 
And there is no doubt that this question contains a hint as to why the nations of the world experience success ahead of Yisrael, explaining this situation as resembling the Creation of the World. Meaning that from the beginning, darkness ruled and afterwards, light.

And so it will be with the nations that go in darkness, their function in this world comes first. And afterwards, the light of Yisrael will fulfill its function.
 
And this is not the place to expand on this topic.

This is a powerful analogy.

As I write this, the sun is shining through the window. Everything looks bright and full of light.

We seem to see everything pretty clearly.

But in reality, we are actually in an existence that is just as unimaginably dark as the universe was before there was any light, neither a spiritual light nor the light from stars and nebulae.

When we follow other nations, we are going in darkness. The only way to be able to grope our way through this darkness is to cling to Torah values (which non-Jews can also do by following the Seven Noachide Laws). But the darkness still remains a solid fact of this current existence. The Torah helps us to keep going, but we can't really see (even if it seems like we can).

Yet eventually –  and hopefully very soon! –  we all will experience the joy of real light.

Rabbi Shlomo Ephraim of Luntschitz (1550-1619) lived in Bohemia (which is today Poland and Czechoslovakia). He served as rabbi and dayan and wrote several books, the most well-known being his commentary on the Chumash known as the Kli Yakar.
This is my translation and any errors are also mine.