William Perkins (1558-1602) was probably the best known and most widely read divine of the Elizabethan period. By the time of his death, Perkins writings were outselling Calvin and Beza. A large part of Perkins studies was taken up with showing men that they must make their calling and election sure to themselves (2 Peter 1:10). Perkins own thinking and theology was heavily influenced by Theodore Beza, who was Calvin’s successor at Geneva (see appendix).
In his exposition of Galatians, Perkins clearly lays out his understanding of the grounds for assurance; first came the general promise of the gospel, by which faith becomes a particular personal promise; secondly the testimony of the Holy Spirit witnessing with our spirit that we are the children of God; and third, the syllogism which rests partly on the gospel and partly on experience. This was patterned on Beza’s views.
There are a number of important areas of Perkins understanding which need clarifying. Firstly Perkins believed in Works of Preparation preceding the Work of Grace. A Christian goes through a process of preparation before he is saved. We shall see how this functions in Perkins understanding in a moment.
Secondly, Perkins definition of assurance needs to be established. It would appear that in his Works 1:125 & 564 Perkins blatantly contradicts himself.
Firstly he says: Whereas some are of the opinion that faith is assurance or confidence, that seems to be otherwise; for it is a fruit of faith…
Then later he writes; True faith is both an unfallible assurance, and a particular assurance of the remission of sins, and of life everlasting…
The problem is that Perkins has divided assurance into two areas, objective and subjective assurance. This is similar to Calvin’s view of the “knowledge of God’s word” and the “work of the Holy Spirit” as two separate stages.
The first usage (…objective assurance) enables the sinner to view the “pardonable-ness” or “forgivable-ness” of his sins apart from the personal realization of such forgiveness, while the second (…subjective assurance) refers to “full’ assurance received in the wake of the personal application of redemption which enables the sinner to believe that God for Christ’s sake personally forgive all his sins. 
 A N S Lane, Calvin’s Doctrine Of Assurance, Vox Evangelica 1979 No 11 pg44