Sex Desire binds the conditioned soul in material existence

Copied from HDG Srila Prabhupada's purport to SB 2.1.12:

How Sex Desire binds?

• The grossest type of anartha which binds the conditioned soul in material existence is sex desire, and this sex desire gradually develops in the union of the male and female.
•  When the male and female are united, the sex desire is further aggravated by the accumulation of buildings, children, friends, relatives and wealth.When all these are acquired, the conditioned soul becomes overwhelmed by such entanglements, and the false sense of egoism, or the sense of “myself” and “mine,” becomes prominent, and the sex desire expands to various political, social, altruistic, philanthropic and many other unwanted engagements, resembling the foam of the sea waves, which becomes very prominent at one time and at the next moment vanishes as quickly as a cloud in the sky. 
• The conditioned soul is encircled by such products, as well as products of sex desire, and therefore bhakti-yoga leads to gradual evaporation of the sex desire, which is summarized in three headings, namely profit, adoration and distinction. 

How Bhakti Yoga helps one overcome sex desire?

• All conditioned souls are mad after these different forms of sex desire, and one shall see for himself how much he has been freed from such material hankerings based primarily on the sex desire. As a person feels his hunger satisfied after eating each morsel of foodstuff, he must similarly be able to see the degree to which he has been freed from sex desire. 
• The sex desire is diminished along with its various forms by the process of bhakti-yoga because bhakti-yoga automatically, by the grace of the Lord, effectively results in knowledge and renunciation, even if the devotee is not materially very well educated. 
• Knowledge means knowing things as they are, and if by deliberation it is found that there are things which are at all unnecessary, naturally the person who has acquired knowledge leaves aside such unwanted things.
•  When the conditioned soul finds by culture of knowledge that material necessities are unwanted things, he becomes detached from such unwanted things. This stage of knowledge is called vairāgya, or detachment from unwanted things. 
• So by the gradual process of devotional service under the guidance of a proper spiritual master, and following the principles of the Bhāgavatam, one must be able at least to control the gross sex desire before one accepts the renounced order of life factually.
• So purification means getting free gradually from sex desire, and this is attained by meditation on the person of the Lord as described herein, beginning from the feet. One should not try to go upwards artificially without seeing for himself how much he has been released from the sex desire. The smiling face of the Lord is the Tenth Canto of Śrīmad-Bhāgavatam, and there are many upstarts who at once try to begin with the Tenth Canto, and especially with the five chapters which delineate the rāsa-līlā of the Lord.