Translated by Ralph Anzarouth and an anonymous friend
Love in General
The basis of love is knowing the object of one’s love, since man cannot love something about which he has no previous knowledge.
This knowledge can be acquired through any one of the five bodily senses: for instance through seeing with his eyes, hearing with his ears, smelling with his nose, tasting with his mouth and touching with his hands. But knowledge can also be acquired by way of something more refined than the body, and this is knowledge gained through one's intellect. This knowledge is the main cause and beginning of love in man. This will come about by way of the eyes, as the philosopher says that sight is the main source of knowledge which influences the will of people. Subsequently, memory will revive and enhance the pleasure, and afterwards, imagination brought about by that pleasurable thought will generate a heartfelt desire for the beloved thing. This longing stems from the belief that he will certainly achieve his desire. This is the origin of the trait of intense and serious love, which according to the philosopher is the root, foundation and key to all the virtues, since all of them stem from love.
King Solomon, peace be upon him, said (Proverbs 12, 1): "A person who loves to receive criticism, also loves knowledge". In other words, a loving person will of his own accord seek self-rebuke and knowledge. Also (Proverbs, 22, 11): "The refined speech of a sincere friend will gain him the affection [even] of king". The loving person will be clearly seen by all to be pure-hearted and soft-spoken, whose actions and friendship are untainted. In King Solomon's book The Song of Songs, the virtue of love is repeatedly emphasized. Concerning his friend (Song of Songs 3, 10): "His inner-self is paved with love". Our Sages of blessed memory said (Talmud Bavli, treatise Sanhedrin 105b): "It is learned in the name of Rabbi Shimon ben Elazar that love overturns the rules of importance, as it is said about Abraham (Genesis 22, 3) 'And Abraham rose early in the morning and saddled his donkey'." Which means that love is the foremost of the virtues, since it cancels and removes self-importance, the major of all flaws; love will also refine the heart and prepare the loving person to behave with alacrity and integrity. For we see that our patriarch Abraham, who has been called "Abraham His loving one", because of his love for his Creator, was not concerned about his personal honor and saddled his donkey himself1. Thus, if one wants to know the difference between the effect of good traits and bad traits, he should first examine whether what he desires to do is motivated by the virtue of love. And in this way (see Proverbs 14, 15) the wise person will weigh up each of his steps, in every action and decision, whether it is good or bad.
We might compare the virtue of love to a bird called corn bunting2, about which scientists have written that when it is brought before a sick person, if that person is about to die, the bird will turn its head away from him, and will not wish to look at him, whilst if the sick person is destined to recover from his illness, the bird will fix its gaze upon him. In the same way, the pure-hearted loving person will not find himself able to look at iniquity (see Habakuk 1, 13) or anything despicable or faulty. And it will always dwell in the paths of righteousness and integrity and with the kind-hearted as the cedars of Lebanon, in which the birds build their nest and it will reveal the power of its perfection more in times of trouble and sorrow than in times of joy and delight, like a burning candle whose light is more visible in a dark and obscure place than in a bright and sunny place; since whenever the situation turns from good to bad its pure love is revealed.
However, we must bear in mind the order of priorities in love. Man must first and foremost love his Creator above all creatures, as it is written (Deut. 5, 6): "And you shall love the Lord your G-d with all your heart and all your soul" and our Sages of blessed memory said (Talmud Bavli, treatise Berachot 54a): "[all your soul means] even if He takes your life". After Him comes love and fear of the human king, since the Scriptures compare the fear of the king to the fear of G-d, as it is written (Proverbs 24, 21): "My son, fear G-d and the sovereign". After him comes the love for one's father and mother, since the Creator compares the awe due to them with the awe due to Him, as it is written (Levit. 19, 3): "Man must fear his mother and father”, all the more he must love them, as nature requires of him. After the love of his parents, comes the requirement to love his fellow man as himself, as it is written (Levit. 19, 5): "And you shall love your fellow man as yourself", including one's compatriots, each person according to his status, since the righteous person certainly deserves to be loved more than the wicked person. It is even fitting to love the wicked people in order to help them to mend their ways, in accordance to what our Sages of blessed memory said (Talmud Bavli, treatise Berachot 10a): "'May sins disappear from the earth (Psalms 104, 35)' it is written 'sins' and not 'sinners'." And we must hate their deeds3.
Thus, we shall discuss love in the order set out above and finally also the love for women.
Notes of the translators:
 Unlike other important persons, Abraham saddled his donkey by himself, out of deep love for Hashem and His commandment.
 A passerine bird similar to the skylark.
 And not them personally.
The whole book Tzemach Tzadik in Hebrew (printed in Rashi characters) can be downloaded in PDF format and read online at Hebrewbooks.org. Chapter 1 about love in general is found at pages 7-9.